The DSS outputs DPI signals via its second video port (VP2). The DPI
output from DSS is 24 bits (RGB888) and is forwarded to an HDMI
transmitter (ITE-IT66121) on the BeaglePlay platform. For audio output,
BeaglePlay uses mcasp1.

Add pinmux info for DSS DPI signals.

Further, add support for HDMI audio and video output.
Signed-off-by: Aradhya Bhatia <a-bhatia1@ti.com>
Link: https://lore.kernel.org/r/20230809084559.17322-6-a-bhatia1@ti.comSigned-off-by: Nishanth Menon <nm@ti.com>