Ethernet : enable 1000Mbps for tinker-board

Change-Id: I053b234da4892c05d54a17dbb94bf99b9c89c3de

Author: yupei_lin

arch/arm/boot/dts/rk3288-tinker-board.dtsi

@@ -206,7 +206,6 @@
 	pinctrl-0 = <&rgmii_pins>;
 	tx_delay = <0x30>;
 	rx_delay = <0x10>;
-	max-speed = <100>;
 	status = "okay";
 };