[GPU] Fix CM kernels not compiled in default build (openvinotoolkit#36528)

### Details:
- openvinotoolkit#36431 made
`OV_GPU_WITH_CM` depend on the `ENABLE_CM_FOR_GPU` macro being defined
at compile time, but added that compile definition only to the
`openvino_intel_gpu_ocl_obj` target. The registry sources
(registry/*_impls.cpp) compile into the main `openvino_intel_gpu_graph`
target, which never received the definition
- Define `ENABLE_CM_FOR_GPU` at the graph module directory scope
(`src/graph/CMakeLists.txt`) via `add_compile_definitions`, so it
reaches both the backend obj targets and the main graph target uniformly

Author: alvoron

src/plugins/intel_gpu/src/graph/CMakeLists.txt

@@ -4,6 +4,10 @@
 
 set(TARGET_NAME "openvino_intel_gpu_graph")
 
+if(ENABLE_CM_FOR_GPU)
+    add_compile_definitions(ENABLE_CM_FOR_GPU)
+endif()
+
 file(GLOB SUBDIRS "${CMAKE_CURRENT_SOURCE_DIR}/impls/*")
 
 find_host_package(Python3 REQUIRED COMPONENTS Interpreter)

src/plugins/intel_gpu/src/graph/impls/ocl/CMakeLists.txt

@@ -8,10 +8,6 @@ ov_gpu_add_backend_target(
     NAME ${TARGET_NAME}
 )
 
-if(ENABLE_CM_FOR_GPU)
-    target_compile_definitions(${TARGET_NAME} PRIVATE ENABLE_CM_FOR_GPU)
-endif()
-
 ov_build_target_faster(${TARGET_NAME} PCH)
 
 if(GPU_RT_TYPE STREQUAL "SYCL")