scsi: ufs-mediatek: Allow unbound mphy

Allow unbound MPHY module since not every MediaTek UFS platform needs
specific MPHY control.

Link: https://lore.kernel.org/r/20200601104646.15436-6-stanley.chu@mediatek.com
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufs-mediatek.c

@@ -113,6 +113,12 @@ static int ufs_mtk_bind_mphy(struct ufs_hba *hba)
 
 	if (err)
 		host->mphy = NULL;
+	/*
+	 * Allow unbound mphy because not every platform needs specific
+	 * mphy control.
+	 */
+	if (err == -ENODEV)
+		err = 0;
 
 	return err;
 }