drm/i915: Make intel_display_suspend atomic, v2.

Calculate all state using a normal transition, but afterwards fudge
crtc->state->active back to its old value. This should still allow
state restore in setup_hw_state to work properly.

Calling intel_set_mode will cause intel_display_set_init_power to be
called, make sure init_power gets set again afterwards.

Changes since v1:
- Fix to compile with v2 of the patch that adds intel_display_suspend.
- Add intel_display_set_init_power.
- Set return value to int to allow error checking.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 7f8fa7f..6d9c771 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -989,7 +989,7 @@
 void intel_mark_busy(struct drm_device *dev);
 void intel_mark_idle(struct drm_device *dev);
 void intel_crtc_restore_mode(struct drm_crtc *crtc);
-void intel_display_suspend(struct drm_device *dev);
+int intel_display_suspend(struct drm_device *dev);
 int intel_crtc_control(struct drm_crtc *crtc, bool enable);
 void intel_crtc_update_dpms(struct drm_crtc *crtc);
 void intel_encoder_destroy(struct drm_encoder *encoder);