Realtek RTL8211E Ethernet PHY

One batch of RTL8211E is slight broken, that needs some special (and
full of magic numbers) tweaking in order to make GbE to operate properly.
The only well-known board that used the broken batch is Pine64+.
Configure it through an Ethernet OF device node.

Optional properties:

- realtek,config-magic-for-pine64:
  Apply some magic configuration from Realtek that works around broken RTL8211E
  PHYs on Pine64+ boards.

Examples:
Pine64+ with broken RTL8211E:
&mdio {
	ext_phy: ethernet-phy@0 {
		reg = <0>;
		realtek,config-magic-for-pine64;
	};
};
