drm/i915: Track the psr dp connector in dev_priv->psr.enabled

Trying to fish that one out through looping is a bit a locking
nightmare. So just set it and use it in the work struct.

v2:
- Don't Oops in psr_work, spotted by Rodrigo.
- Fix compile warning.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@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 c5d157b..d8115c3 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -658,10 +658,11 @@
 	struct intel_connector *connector;
 };
 
+struct intel_dp;
 struct i915_psr {
 	bool sink_support;
 	bool source_ok;
-	bool enabled;
+	struct intel_dp *enabled;
 	bool active;
 	struct delayed_work work;
 };