net: ethernet: aquantia: Low-level hardware interfaces

Add definitions of functions that interface directly with the hardware.
Signed-off-by: NAlexander Loktionov <Alexander.Loktionov@aquantia.com>
Signed-off-by: NDmitrii Tarakanov <Dmitrii.Tarakanov@aquantia.com>
Signed-off-by: NPavel.Belous <Pavel.Belous@aquantia.com>
Signed-off-by: NDmitry Bezrukov <Dmitry.Bezrukov@aquantia.com>
Signed-off-by: NDavid M. VomLehn <vomlehn@texas.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>