[llvm] [AMDGPU] Allow dpp in v_pk_fmac_f16 for GFX9 and GFX10 (PR #144782)

[Joe Nash via llvm-commits]

https://github.com/Sisyph approved this pull request.

It should have [MC] in the commit title or message, since there is no codegen support. 

IsSingle is fine, it suppresses the _e32 suffix on instructions with no VOP3 form, which is this one.

https://github.com/llvm/llvm-project/pull/144782