drm/i915: make backlight info per-connector

Move from dev_priv to connector->panel. We still don't allow multiple
sysfs interfaces, though.

There should be no functional changes, except for a slight reordering of
connector backlight and sysfs destroy calls. (This change happens now
that the backlight device is actually per-connector, even though the
destroy calls became per-connector earlier.)

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Imre Deak <imre.deak@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 8600c31..a2009bf 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1368,13 +1368,8 @@
 	struct intel_overlay *overlay;
 	unsigned int sprite_scaling_enabled;
 
-	/* backlight */
-	struct {
-		int level;
-		bool enabled;
-		spinlock_t lock; /* bl registers and the above bl fields */
-		struct backlight_device *device;
-	} backlight;
+	/* backlight registers and fields in struct intel_panel */
+	spinlock_t backlight_lock;
 
 	/* LVDS info */
 	bool no_aux_handshake;