tc: flower: Refactor matching flags to be more user friendly

tc: flower: Refactor matching flags to be more user friendly

Instead of "magic numbers" we can now specify each flag
by name. Prefix of "no"  (e.g nofrag) unsets the flag,
otherwise it wil be set.

Example:
    # add a flower filter that will drop fragmented packets
    tc filter add dev ens4f0 protocol ip parent ffff: \
            flower \
            src_mac e4:1d:2d:fd:8b:01 \
            dst_mac e4:1d:2d:fd:8b:02 \
            indev ens4f0 \
            ip_flags frag \
    action drop

    # add a flower filter that will drop non-fragmented packets
    tc filter add dev ens4f0 protocol ip parent ffff: \
            flower \
            src_mac e4:1d:2d:fd:8b:01 \
            dst_mac e4:1d:2d:fd:8b:02 \
            indev ens4f0 \
            ip_flags nofrag \
    action drop

Fixes: 22a8f019891c ('tc: flower: support matching flags')
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>