phycore-rk3288: Migrate to OF_UPSTREAM

The phycore-rk3288 can be migrated to OF_UPSTREAM.
Drop redundant device tree files, update MAINTAINERS and
defconfig's DEFAULT_DEVICE_TREE for rockchip vendor prefix accordingly.
Move device tree nodes required for u-boot to rk3288-phycore-rdk-u-boot.dtsi
such as chosen, i2c_eeprom_id and it's alias.

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
diff --git a/arch/arm/dts/rk3288-phycore-rdk-u-boot.dtsi b/arch/arm/dts/rk3288-phycore-rdk-u-boot.dtsi
index 383b383..12096ee 100644
--- a/arch/arm/dts/rk3288-phycore-rdk-u-boot.dtsi
+++ b/arch/arm/dts/rk3288-phycore-rdk-u-boot.dtsi
@@ -2,6 +2,16 @@
 
 #include "rk3288-u-boot.dtsi"
 
+/ {
+	aliases {
+		eeprom0 = &i2c_eeprom_id;
+	};
+
+	chosen {
+		stdout-path = &uart2;
+	};
+};
+
 &dmc {
 	rockchip,num-channels = <2>;
 	rockchip,pctl-timing = <0x29a 0xc8 0x1f8 0x42 0x4e 0x4 0xea 0xa
@@ -29,6 +39,15 @@
 			bootph-all;
 		};
 	};
+
+	/* M24C32-D Identification page */
+	i2c_eeprom_id: eeprom@58 {
+		bootph-all;
+
+		compatible = "atmel,24c32";
+		reg = <0x58>;
+		pagesize = <32>;
+	};
 };
 
 &pinctrl {