net: sparx5: Support offloading of bridge port flooding flags

Though the SparX-5i can control IPv4/6 multicasts separately from non-IP
multicasts, these are all muxed onto the bridge's BR_MCAST_FLOOD flag.

Signed-off-by: Casper Andersson <casper.casan@gmail.com>
Reviewed-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/20220223082700.qrot7lepwqcdnyzw@wse-c0155
Signed-off-by: Jakub Kicinski <kuba@kernel.org>