drm/i915: use drm_i915_private everywhere in the power domain api

The power domains framework is internal to the i915 driver, so pass
drm_i915_private instead of drm_device to its functions.

Also remove a dangling intel_set_power_well() declaration.

No functional change.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index c942dbf..6810041 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1024,9 +1024,9 @@
 	int count;
 	unsigned long domains;
 	void *data;
-	void (*set)(struct drm_device *dev, struct i915_power_well *power_well,
+	void (*set)(struct drm_i915_private *dev_priv, struct i915_power_well *power_well,
 		    bool enable);
-	bool (*is_enabled)(struct drm_device *dev,
+	bool (*is_enabled)(struct drm_i915_private *dev_priv,
 			   struct i915_power_well *power_well);
 };