drm/radeon: fix VMID use tracking

Otherwise we allocate a new VMID on nearly every submit.

Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index c5519ca..4a8ac1c 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -867,6 +867,8 @@
 	struct radeon_fence		*fence;
 	/* last flush or NULL if we still need to flush */
 	struct radeon_fence		*last_flush;
+	/* last use of vmid */
+	struct radeon_fence		*last_id_use;
 };
 
 struct radeon_vm_manager {