arm64: dts: colibri-imx8x: Split pinctrl_hog1

Split pinctrl_hog1 into a second group so CSI_MCLK can be muxed to a
gpio on its own.

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>