[media] V4L: soc-camera: make (almost) all client drivers re-usable outside of the framework

The most important change in this patch is direct linking to struct
soc_camera_link via the client->dev.platform_data pointer. This makes most
of the soc-camera client drivers also usable outside of the soc-camera
framework. After this change all what is needed for these drivers to
function are inclusions of soc-camera headers for some convenience macros,
suitably configured platform data, which is anyway always required, and
loaded soc-camera core module for library functions. If desired, these
library functions can be made generic in the future and moved to a more
neutral location.

The only two client drivers, that still depend on soc-camera are:

mt9t031: it uses struct video_device for its PM. Since no hardware is
available, alternative methods cannot be tested.

ov6650: it uses struct soc_camera_device to pass its sense data back to
the bridge driver. A generic v4l2-subdevice approach should be developed
to perform this.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

include/media/soc_camera.h

@@ -253,14 +253,14 @@ unsigned long soc_camera_apply_board_flags(struct soc_camera_link *icl,
 #include <linux/i2c.h>
 static inline struct video_device *soc_camera_i2c_to_vdev(const struct i2c_client *client)
 {
-	struct soc_camera_device *icd = client->dev.platform_data;
+	struct v4l2_subdev *sd = i2c_get_clientdata(client);
+	struct soc_camera_device *icd = (struct soc_camera_device *)sd->grp_id;
 	return icd ? icd->vdev : NULL;
 }
 
 static inline struct soc_camera_link *soc_camera_i2c_to_link(const struct i2c_client *client)
 {
-	struct soc_camera_device *icd = client->dev.platform_data;
-	return icd ? to_soc_camera_link(icd) : NULL;
+	return client->dev.platform_data;
 }
 
 static inline struct v4l2_subdev *soc_camera_vdev_to_subdev(const struct video_device *vdev)