mlxsw: spectrum_switchdev: Ban PVID change if bridge has a RIF

When traffic passes through a router port, it needs to be assigned a FID
for ASIC to forward correctly. For bridges, this FID used to be the one
corresponding to VLAN 1. In a previous patch, this was changed to
instead use the PVID at the time that the RIF is created. This patch
guards PVID changes after the RIF was introduced.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>