packet: uses kfree_skb() for errors.

consume_skb() isn't for error cases that kfree_skb() is more proper
one.  At this patch, it fixed tpacket_rcv() and packet_rcv() to be
consistent for error or non-error cases letting perf trace its event
properly.

Signed-off-by: Weongyo Jeong <weongyo.linux@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>