[AMDGPU] Add IntrWillReturn to recently added intrinsics

This adds IntrWillReturn to the gfx90a mfma intrinsics, to match all the
other mfma intrinsics, and llvm.amdgcn.live.mask, to match
llvm.amdgcn.ps.live.

Differential Revision: https://reviews.llvm.org/D97675