ARM: dts: remove disable-wp from rk3229-xms6 emmc

Remove the disable-wp attribute from &emmc as it is, according to
Documentation/devicetree/bindings/mmc/mmc-controller.yaml:

    "Not used in combination with eMMC or SDIO."
Suggested-by: Johan Jonker <jbx6244@gmail.com>
Signed-off-by: Justin Swartz <justin.swartz@risingedge.co.za>
Link: https://lore.kernel.org/r/20200406135006.23759-2-justin.swartz@risingedge.co.zaSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm/boot/dts/rk3229-xms6.dts

@@ -137,7 +137,6 @@ &cpu3 {
 
 &emmc {
 	cap-mmc-highspeed;
-	disable-wp;
 	non-removable;
 	status = "okay";
 };