net: phy: aquantia: add support for PHY LEDs

net: phy: aquantia: add support for PHY LEDs

Aquantia Ethernet PHYs got 3 LED output pins which are typically used
to indicate link status and activity.
Add a minimal LED controller driver supporting the most common uses
with the 'netdev' trigger as well as software-driven forced control of
the LEDs.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
[ rework indentation, fix checkpatch error and improve some functions ]
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>