net: aquantia: Ethtool based ring size configuration

Implemented ring size setup, min/max validation and reconfiguration in
runtime.

Signed-off-by: Anton Mikaev <amikaev@aquantia.com>
Signed-off-by: Igor Russkikh <igor.russkikh@aquantia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>