xen/pciback: double lock typo

We called mutex_lock() twice instead of unlocking.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/xen/xen-pciback/vpci.c b/drivers/xen/xen-pciback/vpci.c
index 01222d7..46d140b 100644
--- a/drivers/xen/xen-pciback/vpci.c
+++ b/drivers/xen/xen-pciback/vpci.c
@@ -238,7 +238,7 @@
 			}
 		}
 	}
-	mutex_lock(&vpci_dev->lock);
+	mutex_unlock(&vpci_dev->lock);
 	return found;
 }