media: uvcvideo: Drop unneeded memset() in meta device ioctl handlers

The .vidioc_g_fmt_meta_cap() and .vidioc_enum_fmt_meta_cap() ioctl
handlers for meta capture devices memset the ioctl argument structure to
zero. This is unnecessary as the memory is already zeroed by the V4L2
ioctl core. Drop the memset(), which, in uvc_meta_v4l2_enum_formats(),
also allows further simplification as structure fields don't need to be
saved and restored.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>