diag: Preventing deadlock by adding spin_unlock

Adding spin_unlock_irqrestore in mhi_write to avoid deadlock.

Change-Id: If1525d46066a2bcb49e764852034f39a1419eb44
Signed-off-by: Arun Prakash <app@codeaurora.org>

drivers/char/diag/diagfwd_mhi.c

@@ -521,8 +521,10 @@ static int mhi_write(int id, unsigned char *buf, int len, int ctxt)
 	spin_lock_irqsave(&ch->lock, flags);
 	err = mhi_buf_tbl_add(&diag_mhi[id], TYPE_MHI_WRITE_CH, buf,
 			      len);
-	if (err)
+	if (err) {
+		spin_unlock_irqrestore(&ch->lock, flags);
 		goto fail;
+	}
 
 	err = mhi_queue_transfer(diag_mhi[id].mhi_dev, DMA_TO_DEVICE, buf,
 				len, mhi_flags);