ARM: dts: imx6qdl-apalis/-colibri: assign VDDD to SGTL5000

VDDD is connected to VGEN4 of the PF0100. This rail should only
run at 1.8V since there are multiple consumer and they all
expect the rail to be at 1.8V.

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