ARM: dts: imx27-phytec-phycore-som: Enable AUDMUX

Patch adds AUDMUX routing for Phytec PCM-038 module.
This route i.MX SSI0 (Port 1) to the slave port 4 where MC13783
codec interface is connected.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>