drm/meson: add YUV422 output support

Support YUV422 output from the Amlogic Meson SoC VPU to the HDMI
controller. Without this YUV422 format out of the HDMI encoder
leads to using the dw-hdmi YUV444 to YUV422 color conversion which
gives wrong colors and a green line on the left edge of the screen.

Signed-off-by: Dongjin Kim <tobetter@gmail.com>
Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Tested-by: Furkan Kardame <f.kardame@manjaro.org>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Dan Johansen <strit@manjaro.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220516072245.10745-1-christianshewitt@gmail.com