ARM: dts: mmp2-olpc-xo-1-75: Enable audio support

This enables the audio SRAM, DMA engine, I2S interface, and codec, hooks
them together and adds a audio-graph-card instance.

It also removes the jack gpios from the gpio-keys instance, because the
audio jack driver registers an input device.

Link: https://lore.kernel.org/r/20200718205019.184927-10-lkundrak@v3.sk


Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>