media: imx: Move capture device init to registered

If the CSI is unregistered and then registered again without the
driver being removed and re-probed (which will happen when the media
device is removed and re-probed without also removing/re-probing the
CSI), the result is the kobject error and backtrace "tried to init an
initialized object". This is because the video device is left in an
initialized state after being unregistered, thus the video device's
underlying kobject is also left in an initialized state when the device
is registered again.

Fix this by moving imx_media_capture_device_init() and _remove()
into csi_registered() and csi_unregistered(). This will create a new
un-initialized video device when the CSI is re-registered. Do this for
all the subdevices that register a capture device.

Reported-by: Russell King <linux@armlinux.org.uk>
Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>