V4L/DVB (4746): HM12 is YUV 4:2:0, not YUV 4:1:1

Fix comment in videodev2.h
Signed-off-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

include/linux/videodev2.h

@@ -243,7 +243,7 @@ struct v4l2_pix_format
 #define V4L2_PIX_FMT_YUV420  v4l2_fourcc('Y','U','1','2') /* 12  YUV 4:2:0     */
 #define V4L2_PIX_FMT_YYUV    v4l2_fourcc('Y','Y','U','V') /* 16  YUV 4:2:2     */
 #define V4L2_PIX_FMT_HI240   v4l2_fourcc('H','I','2','4') /*  8  8-bit color   */
-#define V4L2_PIX_FMT_HM12    v4l2_fourcc('H','M','1','2') /*  8  YUV 4:1:1 16x16 macroblocks */
+#define V4L2_PIX_FMT_HM12    v4l2_fourcc('H','M','1','2') /*  8  YUV 4:2:0 16x16 macroblocks */
 
 /* see http://www.siliconimaging.com/RGB%20Bayer.htm */
 #define V4L2_PIX_FMT_SBGGR8  v4l2_fourcc('B','A','8','1') /*  8  BGBG.. GRGR.. */