drm/i915: Re-register PMIC bus access notifier on runtime resume

intel_uncore_suspend() unregisters the uncore code's PMIC bus access
notifier and gets called on both normal and runtime suspend.

intel_uncore_resume_early() re-registers the notifier, but only on
normal resume. Add a new intel_uncore_runtime_resume() function which
only re-registers the notifier and call that on runtime resume.

Cc: stable@vger.kernel.org
Reported-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171114135518.15981-2-hdegoede@redhat.com
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 1ae7031..f4588ad 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -2621,6 +2621,8 @@ static int intel_runtime_resume(struct device *kdev)
 		ret = vlv_resume_prepare(dev_priv, true);
 	}
 
+	intel_uncore_runtime_resume(dev_priv);
+
 	/*
 	 * No point of rolling back things in case of an error, as the best
 	 * we can do is to hope that things will still work (and disable RPM).