net: usb: asix: ax88772: manage PHY PM from MAC

Take over PHY power management, otherwise PHY framework will try to
access ASIX MDIO bus before MAC resume was completed.

Fixes: e532a096

 ("net: usb: asix: ax88772: add phylib support")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Suggested-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>