net: rbridge: simplify br && br->rbr condition

Signed-off-by: William Dauchy <william@gandi.net>
Signed-off-by: Ahmed Amamou <ahmed@gandi.net>
net: bridge: some more coding style

also remove useless return at the end of function

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