drivers: video: introduce the RGB24 format

This introduces the RGB 24-bit format as defined in the Linux header
<include/uapi/linux/videodev2.h>, including the bits-per-pixel size
definition.

Signed-off-by: Josuah Demangeon <me@josuah.net>

Author: josuah

include/zephyr/drivers/video.h

@@ -1292,6 +1292,15 @@ void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep,
  */
 #define VIDEO_PIX_FMT_XRGB32 VIDEO_FOURCC('B', 'X', '2', '4')
 
+/**
+ * Red, Green, Blue, one byte per channel, 24-bits in total.
+ *
+ * @verbatim
+ * | Rrrrrrrr Gggggggg Bbbbbbbb | ...
+ * @endverbatim
+ */
+#define VIDEO_PIX_FMT_RGB24 VIDEO_FOURCC('R', 'G', 'B', '3')
+
 /**
  * @}
  */