ARM: dts: imx6qdl-vicut1.dtsi: Update GPIO line names

Add some missing names and remove names to pins that have never been used
and/or are not present on any hardware.

Signed-off-by: David Jander <david@protonic.nl>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>