Update bad_npu_nd.mlir stride-alignment test to use size>1 dim

The test triggered the "Stride 1 ... not divisible by 4" error using a
size=1 dim with stride=2. After the verifier skips alignment checks for
size==1 dims (their stride is never stepped), that case no longer errors.

Switch the dim's size from 1 to 2 so the same stride violation occurs on
a dim that is actually stepped. Error message is unchanged (same stride
index, same value).

Co-Authored-By: Claude Opus 4 (1M context) <noreply@anthropic.com>

Author: hunhoffe

test/dialect/AIEX/bad_npu_nd.mlir

@@ -140,7 +140,7 @@ module {
       %c2 = arith.constant 2 : i64  // Stride of 2 i8s = 2 bytes < 4 byte granularity, should not be possible
       %c8 = arith.constant 8 : i64
       // expected-error@+1 {{Stride 1 is 2 elements * 1 bytes = 2 bytes, which is not divisible by 4}}
-      aiex.npu.dma_memcpy_nd (%a[%c0,%c0,%c0,%c0][%c1,%c1,%c1,%c8][%c0,%c0,%c2,%c1]) { metadata = @objectfifo, id = 0 : i64 } : memref<8xi8>
+      aiex.npu.dma_memcpy_nd (%a[%c0,%c0,%c0,%c0][%c1,%c1,%c2,%c8][%c0,%c0,%c2,%c1]) { metadata = @objectfifo, id = 0 : i64 } : memref<8xi8>
     }
     %tile_0_0 = aie.tile(0, 0)
     aie.shim_dma_allocation @objectfifo (%tile_0_0, MM2S, 0)