ARM: dts: imx6qdl-apalis/-colibri: remove 1.8V regulator

The fixed 1.8V regulator is not used, and there is in fact no
fixed 1.8V regulator on the module. Remove it.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>