net: dsa: rzn1-a5psw: add vlan support

Add support for vlan operation (add, del, filtering) on the RZN1
driver. The a5psw switch supports up to 32 VLAN IDs with filtering,
tagged/untagged VLANs and PVID for each ports.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>