net: bcmasp: Add support for ASP2.0 Ethernet controller

Add support for the Broadcom ASP 2.0 Ethernet controller which is first
introduced with 72165. This controller features two distinct Ethernet
ports that can be independently operated.

Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Justin Chen <justin.chen@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>