v4l2-ioctl: add a missing break at v4l_fill_fmtdesc()

The changeset ba300204 added a logic at the core to fill
the format description, however, a break is missing on one of
the formats, as reported by smatch:
	drivers/media/v4l2-core/v4l2-ioctl.c:1211 v4l_fill_fmtdesc() warn: missing break? reassigning 'descr'
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/v4l2-core/v4l2-ioctl.c

@@ -1207,7 +1207,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
 	case V4L2_PIX_FMT_SGRBG10DPCM8:	descr = "8-bit Bayer GRGR/BGBG (DPCM)"; break;
 	case V4L2_PIX_FMT_SRGGB10DPCM8:	descr = "8-bit Bayer RGRG/GBGB (DPCM)"; break;
 	case V4L2_PIX_FMT_SBGGR16:	descr = "16-bit Bayer BGBG/GRGR (Exp.)"; break;
-	case V4L2_PIX_FMT_SN9C20X_I420:	descr = "GSPCA SN9C20X I420";
+	case V4L2_PIX_FMT_SN9C20X_I420:	descr = "GSPCA SN9C20X I420"; break;
 	case V4L2_PIX_FMT_SPCA501:	descr = "GSPCA SPCA501"; break;
 	case V4L2_PIX_FMT_SPCA505:	descr = "GSPCA SPCA505"; break;
 	case V4L2_PIX_FMT_SPCA508:	descr = "GSPCA SPCA508"; break;