Allow setting firstfrag as matching option in tc flower classifier.

 # tc filter add dev eth0 protocol ip parent ffff: \
     flower indev eth0 \
        ip_flags firstfrag
     action mirred egress redirect dev eth1
Signed-off-by: NPieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Signed-off-by: NSimon Horman <simon.horman@netronome.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>