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

@@ -906,14 +906,23 @@ void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep,
 #define VIDEO_PIX_FMT_RGB565 VIDEO_FOURCC('R', 'G', 'B', 'P')
 
 /**
- * The first byte is empty (X) for each pixel.
+ * The first byte is empty (X) for each channel.
  *
  * @verbatim
  * | Xxxxxxxx Rrrrrrrr Gggggggg Bbbbbbbb | ...
  * @endverbatim
  */
 #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')
+
 /**
  * @}
  */
@@ -980,6 +989,8 @@ static inline unsigned int video_bits_per_pixel(uint32_t pixfmt)
 	case VIDEO_PIX_FMT_RGB565:
 	case VIDEO_PIX_FMT_YUYV:
 		return 16;
+	case VIDEO_PIX_FMT_RGB24:
+		return 24;
 	case VIDEO_PIX_FMT_XRGB32:
 	case VIDEO_PIX_FMT_XYUV32:
 		return 32;