[IPVS] bug: endianness breakage in ip_vs_ftp

(p[3]<<24) | (p[2]<<16) | (p[1]<<8) | p[0] is not a valid
way to spell get_unaligned((__be32 *)p

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>