drm/bridge: ti-sn65dsi86: remove redundant null check

Because clk_disable_unprepare already checked NULL clock parameter,
so the additional checks are unnecessary, just remove it
Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200930081859.52431-1-vulab@iscas.ac.cn

drivers/gpu/drm/bridge/ti-sn65dsi86.c

@@ -834,8 +834,7 @@ static void ti_sn_bridge_post_disable(struct drm_bridge *bridge)
 {
 	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
 
-	if (pdata->refclk)
-		clk_disable_unprepare(pdata->refclk);
+	clk_disable_unprepare(pdata->refclk);
 
 	pm_runtime_put_sync(pdata->dev);
 }