[NFC] Fix build error: multi-line comment in opencl-c.h (#171953)
Fix build error after enabling cl_ext_float_atomics in downstream target:
opencl-c.h:13798:80: error: multi-line // comment [-Werror,-Wcomment]
13798 | #endif // defined(__opencl_c_ext_fp16_global_atomic_min_max) && \
Patch By: Jinsong Ji <jinsong.ji@intel.com>