lib/tc: Fix sparse warnings.

lib/tc: Fix sparse warnings.

"sparse" complains with the warning 'incorrect type in argument 1
(different base types)' in function nl_parse_flower_ip when parsing a key
flag and in function nl_msg_put_flower_options when writing the key
flag. Fix this by using network byte order when reading and writing key
flags to netlink messages.

Fixes: 83e86606 ("netdev-tc-offloads: Add support for IP fragmentation")
Signed-off-by: Ian Stokes <ian.stokes@intel.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Roi Dayan <roid@mellanox.com>