bng_en: Configure default VNIC

Add functions to add a filter to the VNIC to configure unicast
addresses. Also, add multicast, broadcast, and promiscuous settings
to the default VNIC.

Signed-off-by: Bhargava Marreddy <bhargava.marreddy@broadcom.com>
Reviewed-by: Vikas Gupta <vikas.gupta@broadcom.com>
Reviewed-by: Rajashekar Hudumula <rajashekar.hudumula@broadcom.com>
Link: https://patch.msgid.link/20250919174742.24969-11-bhargava.marreddy@broadcom.com


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