yellowfin: Fix buffer underrun after dev_alloc_skb() failure

yellowfin_init_ring() needs to clean up if dev_alloc_skb() fails and
should pass an error status up to the caller. This also prevents an
buffer underrun if failure occurred in the first iteration.
yellowfin_open() which calls yellowfin_init_ring() should free its
requested irq upon failure.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>