net: rbridge: return value for rbr_fwd_finish is never used

Signed-off-by: William Dauchy <william@gandi.net>
Signed-off-by: Ahmed Amamou <ahmed@gandi.net>
net: rbridge: remove uneeded skb checks

these checks are not needed since we are derefering the skb before

Signed-off-by: William Dauchy <william@gandi.net>
Signed-off-by: Ahmed Amamou <ahmed@gandi.net>