CARP shares protocol number 112 with VRRP (RFC 5798). And the size of
VRRP packet may be smaller than CARP. ipfw_chk() does m_pullup() to at
least sizeof(struct carp_header) and can fail when packet is VRRP. This
leads to packet drop and message about failed pullup attempt.
Also, RFC 5798 defines version 3 of VRRP protocol, this version number
also unsupported by CARP and such check leads to packet drop.
carp_input() does its own checks for protocol version and packet size,
so we can remove these checks to be able pass VRRP packets.
PR: 234207
MFC after: 1 week
5a416ec2ac