[OpenCL] Add support of cl_intel_device_side_avc_motion_estimation extension

Summary:
Documentation can be found at https://www.khronos.org/registry/OpenCL/extensions/intel/cl_intel_device_side_avc_motion_estimation.txt

Patch by Kristina Bessonova


Reviewers: Anastasia, yaxunl, shafik

Reviewed By: Anastasia

Subscribers: arphaman, sidorovd, AlexeySotkin, krisb, bader, asavonic, cfe-commits

Differential Revision: https://reviews.llvm.org/D51484

llvm-svn: 346392