[AMDGPU] Assembler: Move disabled SDWA and DPP instruction into Disable asm variant

Summary: This removes disabled instructions from match tables so we will not match them at all.

Reviewers: tstellarAMD, vpykhtin, artem.tamazov

Subscribers: wdng, nhaehnle, arsenm

Differential Revision: https://reviews.llvm.org/D24452

llvm-svn: 281216