[media] soc-camera: Add and use soc_camera_power_[on|off]() helper functions

Instead of forcing all soc-camera drivers to go through the mid-layer to
handle power management, create soc_camera_power_[on|off]() functions
that can be called from the subdev .s_power() operation to manage
regulators and platform-specific power handling. This allows non
soc-camera hosts to use soc-camera-aware clients.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[g.liakhovetski@gmx.de: fix compile breakage]
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/include/media/soc_camera.h b/include/media/soc_camera.h
index d865dcf..982bfc9 100644
--- a/include/media/soc_camera.h
+++ b/include/media/soc_camera.h
@@ -254,6 +254,16 @@
 unsigned long soc_camera_apply_board_flags(struct soc_camera_link *icl,
 					   const struct v4l2_mbus_config *cfg);
 
+int soc_camera_power_on(struct device *dev, struct soc_camera_link *icl);
+int soc_camera_power_off(struct device *dev, struct soc_camera_link *icl);
+
+static inline int soc_camera_set_power(struct device *dev,
+				       struct soc_camera_link *icl, bool on)
+{
+	return on ? soc_camera_power_on(dev, icl)
+		  : soc_camera_power_off(dev, icl);
+}
+
 /* This is only temporary here - until v4l2-subdev begins to link to video_device */
 #include <linux/i2c.h>
 static inline struct video_device *soc_camera_i2c_to_vdev(const struct i2c_client *client)