bus: sunxi-rsb: unlock on error in sunxi_rsb_read()

Don't forget to unlock before returning an error code.

Fixes: d787dcdb9c8f ('bus: sunxi-rsb: Add driver for Allwinner Reduced Serial Bus')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
index 846bc29..0cfcb39 100644
--- a/drivers/bus/sunxi-rsb.c
+++ b/drivers/bus/sunxi-rsb.c
@@ -342,13 +342,13 @@
 
 	ret = _sunxi_rsb_run_xfer(rsb);
 	if (ret)
-		goto out;
+		goto unlock;
 
 	*buf = readl(rsb->regs + RSB_DATA);
 
+unlock:
 	mutex_unlock(&rsb->lock);
 
-out:
 	return ret;
 }