net: fec: fec_enet_rx_queue(): factor out VLAN handling into separate function fec_enet_rx_vlan()

In order to clean up of the VLAN handling, factor out the VLAN
handling into separate function fec_enet_rx_vlan().

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://patch.msgid.link/20250618-fec-cleanups-v4-11-c16f9a1af124@pengutronix.de


Signed-off-by: Jakub Kicinski <kuba@kernel.org>