net: bridge: extend the process of special frames

This patch extends the processing of frames in the bridge. Currently MRP
frames needs special processing and the current implementation doesn't
allow a nice way to process different frame types. Therefore try to
improve this by adding a list that contains frame types that need
special processing. This list is iterated for each input frame and if
there is a match based on frame type then these functions will be called
and decide what to do with the frame. It can process the frame then the
bridge doesn't need to do anything or don't process so then the bridge
will do normal forwarding.

Signed-off-by: Henrik Bjoernlund <henrik.bjoernlund@microchip.com>
Reviewed-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>