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.za


Signed-off-by: Heiko Stuebner <heiko@sntech.de>