[AMDGPU] Assembler: support v_mac_f32 DPP and SDWA. Move getNamedOperandIdx to AMDGPUBaseInfo.h

Reviewers: artem.tamazov, tstellarAMD

Subscribers: arsenm, kzhuravl, wdng, nhaehnle, yaxunl, tony-tye

Differential Revision: https://reviews.llvm.org/D25084

llvm-svn: 283560
11 files changed