usb: musb: mediatek: don't unregister something that wasn't registered

This function only calls mtk_otg_switch_init() when the ->port_mode
is MUSB_OTG so the clean up code should only call mtk_otg_switch_exit()
for that mode.

Fixes: 0990366b ("usb: musb: Add support for MediaTek musb controller")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/r/Y8/3TqpqiSr0RxFH@kiliSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/mediatek.c

@@ -294,7 +294,8 @@ static int mtk_musb_init(struct musb *musb)
 err_phy_power_on:
 	phy_exit(glue->phy);
 err_phy_init:
-	mtk_otg_switch_exit(glue);
+	if (musb->port_mode == MUSB_OTG)
+		mtk_otg_switch_exit(glue);
 	return ret;
 }