ARM: dts: colibri-imx6: usb dual-role switching

Introduce USBC_DET GPIO based USB dual-role aka device/host switching.

While at it re-work pinmux comment adding SODIMM number to the USBC_DET
entry.

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