packets: Change IP_ARGS interface to take an ovs_be32 instead of a pointer.

packets: Change IP_ARGS interface to take an ovs_be32 instead of a pointer.

An ovs_be32 is a more obvious way to represent an IP address than a
pointer to one.  It is also more type-safe, especially since "sparse" is
able to check that the argument is in network byte order.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>