mlxsw: spectrum: Move PVID code to appropriate place

PVID is a port attribute and should therefore reside in the main driver
file and not the switchdev specific one.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>