media: v4l2-ioctl: clear fields in s_parm

Zero the reserved capture/output array.

Zero the extendedmode (it is never used in drivers).

Clear all flags in capture/outputmode except for V4L2_MODE_HIGHQUALITY,
as that is the only valid flag.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>