qede: Add support for link

This adds basic link functionality to qede - driver still doesn't provide
users with an API to change any link property, but it does request qed to
initialize the link using default configuration, and registers a callback
that allows it to get link notifications.

This patch adds the ability of the driver to set the carrier as active and
to enable traffic as a result of async. link notifications.
Following this patch, driver should be capable of running traffic.

Signed-off-by: Sudarsana Kalluru <Sudarsana.Kalluru@qlogic.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>