[IFB] After ifb_init_one() failed, i is increased. Decrease

It before entering in the loop for freeing the other ifb devices.
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: NJamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ifb.c

@@ -271,6 +271,7 @@ static int __init ifb_init_module(void)
 	for (i = 0; i < numifbs && !err; i++)
 		err = ifb_init_one(i); 
 	if (err) { 
+		i--;
 		while (--i >= 0)
 			ifb_free_one(i);
 	}