ARM: dts: imx6q-apalis: Move pinmux groups to SoM dtsi

GPIO pinmux groups are declared on the module level. Move muxing
them to the same level. It also reduces code duplication.

Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>