llc: llc_cmsg_rcv was getting called after sk_eat_skb.

Received non stream protocol packets were calling llc_cmsg_rcv that used a
skb after that skb was released by sk_eat_skb. This caused received STP
packets to generate kernel panics.

Signed-off-by: Alexandru Juncu <ajuncu@ixiacom.com>
Signed-off-by: Kunjan Naik <knaik@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>