drm/vmwgfx: Fix recently introduced sparse / smatch warnings and errors

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrant <jakob@vmware.com>
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_context.c b/drivers/gpu/drm/vmwgfx/vmwgfx_context.c
index 97aa551..82c41da 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_context.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_context.c
@@ -744,7 +744,7 @@
  * Emits FIFO commands to scrub a binding represented by @cb.
  * Then stops tracking the binding and re-initializes its storage.
  */
-void vmw_context_binding_kill(struct vmw_ctx_binding *cb)
+static void vmw_context_binding_kill(struct vmw_ctx_binding *cb)
 {
 	(void) vmw_scrub_funcs[cb->bi.bt](&cb->bi);
 	vmw_context_binding_drop(cb);