ARM: dts: imx6qdl-apalis/-colibri: remove unused pinctrl groups

100/200MHz states for USDHC3 are not required since the SoC
does not support modes faster than DDR52 for the on board eMMC.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>