drm/msm: Fix objtool warning in submit_lock_objects()

drm/msm: Fix objtool warning in submit_lock_objects()

Split the vmbind case into a separate helper function
submit_lock_objects_vmbind() to fix objtool warning:

  drivers/gpu/drm/msm/msm.o: warning: objtool: submit_lock_objects+0x451:
  sibling call from callable instruction with modified stack frame

The drm_exec_until_all_locked() macro uses computed gotos internally
for its retry loop. Having return statements inside this macro, or
immediately after it in certain code paths, confuses objtool's static
analysis of stack frames, causing it to incorrectly flag tail call
optimizations.

Fixes: 92395af63a99 ("drm/msm: Add VM_BIND submitqueue")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Patchwork: https://patchwork.freedesktop.org/patch/667539/
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>