[IPV4]: annotate struct in_ifaddr

ifa_local, ifa_address, ifa_mask, ifa_broadcast and ifa_anycast are
net-endian.  Annotated them and variables that are inferred to be
net-endian.

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