dt-bindings: adv748x: add information about serial audio interface (I2S/TDM)

As the driver has some support for the audio interface of the device,
the bindings file should mention it.

Signed-off-by: Alexander Riesen <alexander.riesen@cetitec.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>


v3: remove optionality off MCLK clock cell to ensure the description
    matches the hardware no matter if the line is connected.
    Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
1 file changed