net: enetc: move generic VLAN hash filter functions to enetc_pf_common.c

net: enetc: move generic VLAN hash filter functions to enetc_pf_common.c

The VLAN hash filters of ENETC v1 and v4 are basically the same, the only
difference is that the offset of the VLAN hash filter registers has been
changed in ENETC v4. So some functions like enetc_vlan_rx_add_vid() and
enetc_vlan_rx_del_vid() only need to be slightly modified to be reused
by ENETC v4. Currently, we just move these functions from enetc_pf.c to
enetc_pf_common.c. Appropriate modifications will be made for ENETC4 in
a subsequent patch.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20250506080735.3444381-13-wei.fang@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>