net: enetc: add interfaces to manage dynamic FDB entries

net: enetc: add interfaces to manage dynamic FDB entries

Add three interfaces to manage dynamic entries in the FDB table:

ntmp_fdbt_update_activity_element(): Update the activity element of all
dynamic FDB entries. For each entry, if its activity flag is not set,
which means no packet has matched this entry since the last update, the
activity counter is incremented. Otherwise, both the activity flag and
activity counter are reset. The activity counter is used to track how
long an FDB entry has been inactive, which is useful for implementing
an ageing mechanism.

ntmp_fdbt_delete_ageing_entries(): Delete all dynamic FDB entries whose
activity flag is not set and whose activity counter is greater than or
equal to the specified threshold. This is used to remove stale entries
that have been inactive for too long.

ntmp_fdbt_delete_port_dynamic_entries(): Delete all dynamic FDB entries
associated with the specified switch port. This is typically called when
a port goes down or is removed from a bridge.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
Link: https://patch.msgid.link/20260611021458.2629145-2-wei.fang@oss.nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>