net: renesas: rswitch: add modifiable ageing time

Allow the setting of the MAC table aging in the R-Car S4 Rswitch
using the SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME attribute.

Signed-off-by: Michael Dege <michael.dege@renesas.com>
Link: https://patch.msgid.link/20250901-add_l2_switching-v5-4-5f13e46860d5@renesas.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>