[AMDGPU][MC] Added PCK variants of image load/store instructions

See bug 36834: https://bugs.llvm.org/show_bug.cgi?id=36834

Differential Revision: https://reviews.llvm.org/D44795

Reviewers: artem.tamazov, arsenm, timcorringham, nhaehnle

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@328710 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed