[llvm] AMDGPU: Fix verifier error on tail call target in vgprs (PR #110984)

[Matt Arsenault via llvm-commits]

arsenm wrote:

@sameerds I don't understand the verifier error. The CONVERGENCE_CTRL entry has an assigned register, and is used on all the convergent operations.

https://github.com/llvm/llvm-project/pull/110984