net: dsa: microchip: ksz8: fix MDB configuration with non-zero VID

FID is directly mapped to VID. However, configuring a MAC address with a
VID != 0 resulted in incorrect configuration due to an incorrect bit
mask. This kernel commit fixed the issue by correcting the bit mask and
ensuring proper configuration of MAC addresses with non-zero VID.

Fixes: 4b20a07e ("net: dsa: microchip: ksz8795: add support for ksz88xx chips")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>