Fix warning around ununsed code in QNN Android Emulator builds by clang (#27026)

### Description
As title

### Motivation and Context
Keep CI check happy

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: hariharans29

onnxruntime/test/providers/qnn/bf16_op_test.cc

@@ -14,11 +14,8 @@ namespace onnxruntime {
 namespace test {
 
 // Helper function to create a simple Add model for BF16 testing
-static GetTestModelFn BuildBF16AddTestCase(const TestInputDef<float>& input1_def,
-                                           const TestInputDef<float>& input2_def) {
-  // Silence unused function warning
-  (void)BuildBF16AddTestCase;
-
+[[maybe_unused]] static GetTestModelFn BuildBF16AddTestCase(const TestInputDef<float>& input1_def,
+                                                            const TestInputDef<float>& input2_def) {
   return [input1_def, input2_def](ModelTestBuilder& builder) {
     NodeArg* input1 = MakeTestInput(builder, input1_def);
     NodeArg* input2 = MakeTestInput(builder, input2_def);
@@ -28,11 +25,8 @@ static GetTestModelFn BuildBF16AddTestCase(const TestInputDef<float>& input1_def
 }
 
 // Helper function to create a simple MatMul model for BF16 testing
-static GetTestModelFn BuildBF16MatMulTestCase(const TestInputDef<float>& input1_def,
-                                              const TestInputDef<float>& input2_def) {
-  // Silence unused function warning
-  (void)BuildBF16MatMulTestCase;
-
+[[maybe_unused]] static GetTestModelFn BuildBF16MatMulTestCase(const TestInputDef<float>& input1_def,
+                                                               const TestInputDef<float>& input2_def) {
   return [input1_def, input2_def](ModelTestBuilder& builder) {
     NodeArg* input1 = MakeTestInput(builder, input1_def);
     NodeArg* input2 = MakeTestInput(builder, input2_def);
@@ -42,11 +36,8 @@ static GetTestModelFn BuildBF16MatMulTestCase(const TestInputDef<float>& input1_
 }
 
 // Helper function to create a Conv model for BF16 testing
-static GetTestModelFn BuildBF16ConvTestCase(const TestInputDef<float>& input_def,
-                                            const TestInputDef<float>& weights_def) {
-  // Silence unused function warning
-  (void)BuildBF16ConvTestCase;
-
+[[maybe_unused]] static GetTestModelFn BuildBF16ConvTestCase(const TestInputDef<float>& input_def,
+                                                             const TestInputDef<float>& weights_def) {
   return [input_def, weights_def](ModelTestBuilder& builder) {
     NodeArg* input = MakeTestInput(builder, input_def);
     NodeArg* weights = MakeTestInput(builder, weights_def);
@@ -56,13 +47,11 @@ static GetTestModelFn BuildBF16ConvTestCase(const TestInputDef<float>& input_def
 }
 
 // Helper function to run BF16 model test
-static void RunBF16ModelTest(const GetTestModelFn& build_test_case,
-                             const std::vector<int64_t>& input_shape,
-                             ExpectedEPNodeAssignment expected_ep_assignment = ExpectedEPNodeAssignment::All,
-                             int opset = 18,
-                             float fp32_abs_err = 1e-2f) {
-  // Silence unused function warning
-  (void)RunBF16ModelTest;
+[[maybe_unused]] static void RunBF16ModelTest(const GetTestModelFn& build_test_case,
+                                              const std::vector<int64_t>& input_shape,
+                                              ExpectedEPNodeAssignment expected_ep_assignment = ExpectedEPNodeAssignment::All,
+                                              int opset = 18,
+                                              float fp32_abs_err = 1e-2f) {
   ORT_UNUSED_PARAMETER(input_shape);
 
   ProviderOptions provider_options;