media: vim2m: fix two double-free issues

vim2m_device_release() will be called by video_unregister_device() to release
various objects.

There are two double-free issue,
1. dev->m2m_dev will be freed twice in error_m2m path/vim2m_device_release
2. the error_v4l2 and error_free path in vim2m_probe() will release
   same objects, since vim2m_device_release has done.

Fixes: ea6c7e34

 ("media: vim2m: replace devm_kzalloc by kzalloc")

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>