arm64: dts: rockchip: add the readable and writable for rk3399 linux

There are some progresses need the readable and writable, when the debian
rootfs brings up.

Change-Id: I0f3b4fab5d591e35f5aacb4901f4e7733e46c306
Signed-off-by: Caesar Wang <[email protected]>

Author: Caesar-github

arch/arm64/boot/dts/rockchip/rk3399-linux.dtsi

@@ -47,7 +47,7 @@
 	compatible = "rockchip,linux", "rockchip,rk3399";
 
 	chosen {
-		bootargs = "earlycon=uart8250,mmio32,0xff1a0000 swiotlb=1 console=ttyFIQ0 root=PARTUUID=614e0000-0000 rootfstype=ext4 rootwait";
+		bootargs = "earlycon=uart8250,mmio32,0xff1a0000 swiotlb=1 console=ttyFIQ0 rw root=PARTUUID=614e0000-0000 rootfstype=ext4 rootwait";
 	};
 
 	reserved-memory {