ARM: dts: rockchip: add en 2t mode for rk3128

Disable it default, because we found it is unstable when using
some ddr chip.

Change-Id: Iffd98a0f5ab9c9256ec9a1450ce105a5b7f6127b
Signed-off-by: Huibin Hong <[email protected]>

Author: Huibin Hong

arch/arm/boot/dts/rk3128-dram-default-timing.dtsi

@@ -68,5 +68,6 @@
 		phy_lpddr2_clk_drv = <PHY_RON_44ohm>;
 		phy_lpddr2_cmd_drv = <PHY_RON_44ohm>;
 		phy_lpddr2_dqs_drv = <PHY_RON_44ohm>;
+		ddr_2t = <0>;
 	};
 };