media: strscpy() returns a negative value on failure unlike strlcpy().

strscpy() returns a negative value on failure unlike strlcpy(),
so fix the WARN_ON accordingly.
Signed-off-by: Hans Petter Selasky <hps@selasky.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil-cisco@xs4all.nl: added commit message]
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

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

@@ -1373,7 +1373,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
 	}
 
 	if (descr)
-		WARN_ON(strscpy(fmt->description, descr, sz) >= sz);
+		WARN_ON(strscpy(fmt->description, descr, sz) < 0);
 	fmt->flags = flags;
 }