net: rbridge: remove unused function

Signed-off-by: François Cachereul <f.cachereul@alphalink.fr>
Signed-off-by: Ahmed Amamou <ahmed@gandi.net>
net: rbridge: remove unused function

There is byte shift if skb->encapsulation is already set.
This happen when using another encapsulation protocol (like for example
vxlan) on the same system.

Signed-off-by: François Cachereul <f.cachereul@alphalink.fr>
Signed-off-by: Ahmed Amamou <ahmed@gandi.net>