[NPUW] restored npu-unit-tests with avx2 (#31998)

### Details:
- related to PR: #30899

### Tickets:
 - *ticket-id*

Co-authored-by: Alexander Kalistratov <[email protected]>

Author: esmirno

src/plugins/intel_npu/tests/unit/CMakeLists.txt

@@ -48,6 +48,7 @@ ov_add_test_target(
 if(ENABLE_AVX2)
     ov_avx2_optimization_flags(avx2_flags)
     target_compile_options(${TARGET_NAME} PRIVATE "${avx2_flags}")
+    target_compile_definitions(${TARGET_NAME} PRIVATE HAVE_AVX2)
 endif()
 
 install(TARGETS ${TARGET_NAME}