ARM: dts: kzm9d: Add rw parameter to bootargs

Add rw as bootargs parameter to make the KZM9D board bootargs match other
boards from Renesas. No need to be special.
Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/emev2-kzm9d.dts

@@ -25,7 +25,7 @@ aliases {
 	};
 
 	chosen {
-		bootargs = "ignore_loglevel root=/dev/nfs ip=dhcp";
+		bootargs = "ignore_loglevel rw root=/dev/nfs ip=dhcp";
 		stdout-path = "serial1:115200n8";
 	};