drm/amdgpu:insert switch buffer only for VM submit

for non-VM submit which is from kernel side, no need
to switch buffer at all.

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c

@@ -224,7 +224,7 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
 		amdgpu_ring_patch_cond_exec(ring, patch_offset);
 
 	ring->current_ctx = fence_ctx;
-	if (ring->funcs->emit_switch_buffer)
+	if (vm && ring->funcs->emit_switch_buffer)
 		amdgpu_ring_emit_switch_buffer(ring);
 	amdgpu_ring_commit(ring);
 	return 0;