[media] uvcvideo: Add GUID for BGR 8:8:8

The Magewell XI100DUSB-HDMI[1] video capture device reports the pixel
format "e436eb7d-524f-11ce-9f53-0020af0ba770".  This is its GUID for
BGR 8:8:8.

The UVC 1.5 spec[2] only defines GUIDs for YUY2, NV12, M420 and I420.
This seems to be an extension documented in the Microsoft Windows Media
Format SDK[3] - or at least the Media Format SDK was the only hit that
Google gave when searching for the GUID.  This Media Format SDK defines
this GUID as corresponding to `MEDIASUBTYPE_RGB24`.  Note though, the
XI100DUSB outputs BGR e.g. byte-reversed.  I don't know if its the
capture device in error or Microsoft mean BGR when they say RGB.

[1]: http://www.magewell.com/hardware/dongles/xi100dusb-hdmi/xi100dusb-hdmi_features.html?lang=en
[2]: http://www.usb.org/developers/docs/devclass_docs/USB_Video_Class_1_5.zip
[3]: http://msdn.microsoft.com/en-gb/library/windows/desktop/dd757532(v=vs.85).aspx

Signed-off-by: William Manley <will@williammanley.net>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/uvc/uvc_driver.c

@@ -137,6 +137,11 @@ static struct uvc_format_desc uvc_fmts[] = {
 		.guid		= UVC_GUID_FORMAT_RGBP,
 		.fcc		= V4L2_PIX_FMT_RGB565,
 	},
+	{
+		.name		= "BGR 8:8:8 (BGR3)",
+		.guid		= UVC_GUID_FORMAT_BGR3,
+		.fcc		= V4L2_PIX_FMT_BGR24,
+	},
 	{
 		.name		= "H.264",
 		.guid		= UVC_GUID_FORMAT_H264,

drivers/media/usb/uvc/uvcvideo.h

@@ -109,6 +109,9 @@
 #define UVC_GUID_FORMAT_RGBP \
 	{ 'R',  'G',  'B',  'P', 0x00, 0x00, 0x10, 0x00, \
 	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
+#define UVC_GUID_FORMAT_BGR3 \
+	{ 0x7d, 0xeb, 0x36, 0xe4, 0x4f, 0x52, 0xce, 0x11, \
+	 0x9f, 0x53, 0x00, 0x20, 0xaf, 0x0b, 0xa7, 0x70}
 #define UVC_GUID_FORMAT_M420 \
 	{ 'M',  '4',  '2',  '0', 0x00, 0x00, 0x10, 0x00, \
 	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}