Some IPs like the meson VPU can only feed a particular pixel format to
dw_hdmi. As of now, the driver is hardcoded to use RGB888 as input.

This commit enables different pixel format inputs, with the appropriate
CSC configuration.
Signed-off-by: NJorge Ramire-Ortiz <jramirez@baylibre.com>
Signed-off-by: NMaxime Jourdan <mjourdan@baylibre.com>
Signed-off-by: NNeil Armstrong <narmstrong@baylibre.com>
Reviewed-by: NAnatolij Gustschin <agust@denx.de>