[PATCH net] liquidio: silence a locking static checker warning

[Dan Carpenter]

Presumably we never hit this return, but static checkers complain that
we need to unlock so we may as well fix that.

Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>

diff --git a/drivers/net/ethernet/cavium/liquidio/octeon_mailbox.c 
b/drivers/net/ethernet/cavium/liquidio/octeon_mailbox.c
index 201b9875f9bb..5cca73b8880b 100644
--- a/drivers/net/ethernet/cavium/liquidio/octeon_mailbox.c
+++ b/drivers/net/ethernet/cavium/liquidio/octeon_mailbox.c
@@ -313,6 +313,7 @@ int octeon_mbox_process_message(struct octeon_mbox *mbox)
                return 0;
        }
 
+       spin_unlock_irqrestore(&mbox->lock, flags);
        WARN_ON(1);
 
        return 0;