media: mc: Clear minor number before put device

The device minor should not be cleared after the device is released.

Fixes: 9e14868dc952 ("media: mc: Clear minor number reservation at unregistration time")
Cc: stable@vger.kernel.org
Reported-by:  <syzbot+031d0cfd7c362817963f@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=031d0cfd7c362817963f


Tested-by:  <syzbot+031d0cfd7c362817963f@syzkaller.appspotmail.com>
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>