ARM: dts: imx6qdl-icore-rqs: Switch to use simple-audio-card

This patch replace fsl,imx-audio-sgtl5000 and use simple-audio-card
for Engicam i.CoreM6 RQS QDL platform boards.

This patch also fix, pinctrl_adumux.

Cc: Matteo Lisi <matteo.lisi@engicam.com>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>