This commit adds new intrinsics
llvm.amdgcn.tbuffer2.load llvm.amdgcn.tbuffer2.store
with combined operands for format (dfmt+nfmt) and cachepolicy (glc+slc).
The AMDISD::TBUFFER_* SD nodes have changed correspondingly.
The obsolescent llvm.amdgcn.tbuffer.* and llvm.SI.tbuffer.store
intrinsics continue to work.
Change-Id: If22ad77e349fac3a5d2f72dda53c010377d470d4