[AMDGPU] Mark SMRD atomics

We did not have atomic flags on SMRD, did not copy TSFlags
to real instructions, and did not have ret/noret atomic map.

At the moment it is NFC, but needed for D96469.

Differential Revision: https://reviews.llvm.org/D96823

GitOrigin-RevId: 48d2e04152366890e0b219a5f7c6f5b4905af480
1 file changed