Amlogic Unifykey

Required properties:
 - compatible: must be "amlogic,unifykey"

 - status: should be "okay" or "disabled"

 - key_n: property defination of each key, which contains key-name, key-device and key-permit
	 	key-name could be any ascii string within 48 bytes
		key-device must be one of "normal", "secure", "efuse"
		key-permit must be the combination of "read", "write" and "del"

Examples:

	unifykey {
		compatible = "amlogic,unifykey";
		status = "okay";

		key_0{
			key-name = "usid";
			key-device = "normal";
			key-permit = "read", "write", "del";
		};
		key_1{
			key-name = "mac";
			key-device = "normal";
			key-permit = "read", "write", "del";
		};
	};
