drm/sun4i: Release exclusive clock lock when disabling TCON

Currently exclusive TCON clock lock is never released, which, for
example, prevents changing resolution on HDMI.

In order to fix that, release clock when disabling TCON. TCON is always
disabled first before new mode is set.
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180301213442.16677-7-jernej.skrabec@siol.net

drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -101,10 +101,12 @@ static void sun4i_tcon_channel_set_status(struct sun4i_tcon *tcon, int channel,
 		return;
 	}
 
-	if (enabled)
+	if (enabled) {
 		clk_prepare_enable(clk);
-	else
+	} else {
+		clk_rate_exclusive_put(clk);
 		clk_disable_unprepare(clk);
+	}
 }
 
 static void sun4i_tcon_lvds_set_status(struct sun4i_tcon *tcon,