Revert "ayufan: dts: rockpro64: disable tx offloading to improve gmac stability"

This reverts commit 0642f6c.

Author: ayufan

arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dts

@@ -274,7 +274,6 @@
 	phy-mode = "rgmii";
 	pinctrl-names = "default";
 	pinctrl-0 = <&rgmii_pins>;
-	snps,force_thresh_dma_mode;
 	snps,reset-gpio = <&gpio3 RK_PB7 GPIO_ACTIVE_LOW>;
 	snps,reset-active-low;
 	snps,reset-delays-us = <0 10000 50000>;