ARM: dts: rockchip: clean up the abuse of disable-wp

The mmc.txt didn't explicitly say disable-wp is for SD card slot
only, but that is what it was designed for in the first place.

Remove all disable-wp from emmc or sdio controller.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>