AMDGPU/R600: Implement allowsMisalignedMemoryAccess

This avoids some test regressions in a future commit
when unaligned operations are expanded when they
have custom lowering.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261570 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed