[llvm] [AMDGPU] op_sel[0] must be zero for v_cvt_sr_fp8/bf8_f16 (PR #227413)

[Changpeng Fang via llvm-commits]

changpeng wrote:

> Are these instructions only supported by one target? If no, do all of them have this hazard?

Multiple targets including downstream ones. All SP3 specs have been updated to specify
opsel[0] == 0 (OPF_NOOPSEL_0)

https://github.com/llvm/llvm-project/pull/227413