OMAPDSS: DISPC: use WARN_ON() in dispc_mgr_go

dispc_mgr_go() should never be called with manager output disabled or if
the GO bit is already set. Change the current silent returns to
WARN_ONs.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/dss/dispc.c

@@ -569,20 +569,8 @@ bool dispc_mgr_go_busy(enum omap_channel channel)
 
 void dispc_mgr_go(enum omap_channel channel)
 {
-	bool enable_bit, go_bit;
-
-	/* if the channel is not enabled, we don't need GO */
-	enable_bit = mgr_fld_read(channel, DISPC_MGR_FLD_ENABLE) == 1;
-
-	if (!enable_bit)
-		return;
-
-	go_bit = mgr_fld_read(channel, DISPC_MGR_FLD_GO) == 1;
-
-	if (go_bit) {
-		DSSERR("GO bit not down for channel %d\n", channel);
-		return;
-	}
+	WARN_ON(dispc_mgr_is_enabled(channel) == false);
+	WARN_ON(dispc_mgr_go_busy(channel));
 
 	DSSDBG("GO %s\n", mgr_desc[channel].name);