media: uapi: Document format MEDIA_BUS_FMT_RGB565_1X24_CPADHI

Add support for MEDIA_BUS_FMT_RGB565_1X24_CPADHI. This format is used
by the Geekworm MZP280 panel which interfaces with the Raspberry Pi.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>