[OpenCL] Undefine cl_intel_planar_yuv extension
Remove unnecessary definition (otherwise the extension will be defined
where it's not supposed to be defined).
Consider the code:
#pragma OPENCL EXTENSION cl_intel_planar_yuv : begin // some declarations #pragma OPENCL EXTENSION cl_intel_planar_yuv : end
is enough for extension to become known for clang.
Patch by: Dmitry Sidorov <firstname.lastname@example.org>
Reviewers: Anastasia, yaxunl
Reviewed By: Anastasia
Differential Revision: https://reviews.llvm.org/D58666