[llvm] [AMDGPU][MC] GFX9 - allow op_sel in v_interp_p2_f16 (PR #150712)

[Jun Wang via llvm-commits]

jwanggit86 wrote:

In the printer, check for this special case, i.e., instructions with src0, src2 but no src1, and ensure 4 bits for op_sel are printed. For src1 print the default value.

https://github.com/llvm/llvm-project/pull/150712