iavf: stop removing VLAN filters from PF on interface down

iavf: stop removing VLAN filters from PF on interface down

When a VF goes down, the driver currently sends DEL_VLAN to the PF for
every VLAN filter (ACTIVE -> DISABLE -> send DEL -> INACTIVE), then
re-adds them all on UP (INACTIVE -> ADD -> send ADD -> ADDING ->
ACTIVE). This round-trip is unnecessary because:

 1. The PF disables the VF's queues via VIRTCHNL_OP_DISABLE_QUEUES,
    which already prevents all RX/TX traffic regardless of VLAN filter
    state.

 2. The VLAN filters remaining in PF HW while the VF is down is
    harmless - packets matching those filters have nowhere to go with
    queues disabled.

 3. The DEL+ADD cycle during down/up creates race windows where the
    VLAN filter list is incomplete. With spoofcheck enabled, the PF
    enables TX VLAN filtering on the first non-zero VLAN add, blocking
    traffic for any VLANs not yet re-added.

Remove the entire DISABLE/INACTIVE state machinery:
 - Remove IAVF_VLAN_DISABLE and IAVF_VLAN_INACTIVE enum values
 - Remove iavf_restore_filters() and its call from iavf_open()
 - Remove VLAN filter handling from iavf_clear_mac_vlan_filters(),
   rename it to iavf_clear_mac_filters()
 - Remove DEL_VLAN_FILTER scheduling from iavf_down()
 - Remove all DISABLE/INACTIVE handling from iavf_del_vlans()

VLAN filters now stay ACTIVE across down/up cycles. Only explicit
user removal (ndo_vlan_rx_kill_vid) or PF/VF reset triggers VLAN
filter deletion/re-addition.

Fixes: ed1f5b58ea01 ("i40evf: remove VLAN filters on close")
Signed-off-by: Petr Oros <poros@redhat.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260427-jk-iwl-net-petr-oros-fixes-v1-2-cdcb48303fd8@intel.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>