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 <[e-mail]>
Signed-off-by: Sam Ravnborg <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

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

···
 {
 	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);
 }