media: uvcvideo: Do not mark valid metadata as invalid

media: uvcvideo: Do not mark valid metadata as invalid

Currently, the driver performs a length check of the metadata buffer
before the actual metadata size is known and before the metadata is
decided to be copied. This results in valid metadata buffers being
incorrectly marked as invalid.

Move the length check to occur after the metadata size is determined and
is decided to be copied.

Cc: stable@vger.kernel.org
Fixes: 088ead255245 ("media: uvcvideo: Add a metadata device node")
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Link: https://lore.kernel.org/r/20250707-uvc-meta-v8-1-ed17f8b1218b@chromium.org
Signed-off-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>