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

[Jun Wang via llvm-commits]

jwanggit86 wrote:

> Can you please add a few assembly tests with 3 values in op_sel? like `'... op_sel:[1,0,1]'`
> 
> With that LGTM

Added 3 bits tests.

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