remove CL_DEVICE_HALF_FP_CONFIG
remove CL_DEVICE_HALF_FP_CONFIG

"cl_khr_fp16" is still included as an extension in higher OpenCL versions unlike "cl_khr_fp64"  
which is an optional-core feature from OpenCL 1.2. Hence remove the above defined macro  
as it is already defined in "cl_ext.h"
KhronosGroup/OpenCL-Headers,KhronosGroup/OpenCL-Headers