drm/i915: add opregion function to notify bios of adapter power state

Notifying the bios lets it enter power saving states.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
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 3b7368d..769c138 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2197,6 +2197,8 @@
 extern void intel_opregion_asle_intr(struct drm_device *dev);
 extern int intel_opregion_notify_encoder(struct intel_encoder *intel_encoder,
 					 bool enable);
+extern int intel_opregion_notify_adapter(struct drm_device *dev,
+					 pci_power_t state);
 #else
 static inline void intel_opregion_init(struct drm_device *dev) { return; }
 static inline void intel_opregion_fini(struct drm_device *dev) { return; }
@@ -2206,6 +2208,11 @@
 {
 	return 0;
 }
+static inline int
+intel_opregion_notify_adapter(struct drm_device *dev, pci_power_t state)
+{
+	return 0;
+}
 #endif
 
 /* intel_acpi.c */