arm64: dts: colibri-imx8x: fix eval board pin configuration

Fix pinctrl groups to have SODIMM 75 only in one group.
Remove configuration of the pin at SoM level because it is normally
used as CSI_MCLK at camera interface connector.
Without this fix it is not possible, without redefining iomuxc pinctrl,
to use CSI_MCLK signal and leads to the following error messages:

imx8qxp-pinctrl scu:pinctrl: pin IMX8QXP_CSI_MCLK already requested
imx8qxp-pinctrl scu:pinctrl: pin-147 (16-003c) status -22

Fixes: 4d2adf73 ("arm64: dts: colibri-imx8x: Split pinctrl_hog1")
Signed-off-by: Emanuele Ghidoli <emanuele.ghidoli@toradex.com>
Signed-off-by: Andrejs Cainikovs <andrejs.cainikovs@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>