media: vicodec: add missing v4l2_ctrl_request_hdl_put()

The check for a required control in the request was missing a call to
v4l2_ctrl_request_hdl_put(), so the control request object was never
released.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Fixes: 997deb81 ("media: vicodec: Add support for stateless decoder.")
Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>