Fix VIDIOC_ENUMSTD bug

The v4l2 API documentation for VIDIOC_ENUMSTD says:

	To enumerate all standards applications shall begin at index
	zero, incrementing by one until the driver returns EINVAL.

The actual code, however, tests the index this way:

               if (index<=0 || index >= vfd->tvnormsize) {
                        ret=-EINVAL;

So any application which passes in index=0 gets EINVAL right off the bat
- and, in fact, this is what happens to mplayer.  So I think the
following patch is called for, and maybe even appropriate for a 2.6.18.x
stable release.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/media/video/videodev.c

@@ -836,7 +836,7 @@ static int __video_do_ioctl(struct inode *inode, struct file *file,
 			break;
 		}
 
-		if (index<=0 || index >= vfd->tvnormsize) {
+		if (index < 0 || index >= vfd->tvnormsize) {
 			ret=-EINVAL;
 			break;
 		}