Fix check-sycl (may be used uninitialized warning)

Author: aelovikov-intel

sycl/include/sycl/ext/oneapi/experimental/work_group_memory.hpp

@@ -77,7 +77,7 @@ class __SYCL_SPECIAL_CLASS __SYCL_TYPE(work_group_memory) work_group_memory
   void __init(decoratedPtr ptr) { this->ptr = ptr; }
 #endif
 private:
-  decoratedPtr ptr;
+  decoratedPtr ptr = nullptr;
 };
 } // namespace ext::oneapi::experimental
 } // namespace _V1