drm/i915/guc: Disable rpm wakeref asserts in GuC irq handler

We're seeing "RPM wakelock ref not held during HW access" warning
otherwise. Since IRQs are synced for runtime suspend we can just disable
the wakeref asserts.

Reported-by: Marta Löfstedt <marta.lofstedt@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105710
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180714173703.7894-1-chris@chris-wilson.co.uk
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_guc.c

@@ -466,11 +466,13 @@ void intel_guc_to_host_event_handler_mmio(struct intel_guc *guc)
 	 * could happen that GuC sets the bit for 2nd interrupt but Host
 	 * clears out the bit on handling the 1st interrupt.
 	 */
+	disable_rpm_wakeref_asserts(dev_priv);
 	spin_lock(&guc->irq_lock);
 	val = I915_READ(SOFT_SCRATCH(15));
 	msg = val & guc->msg_enabled_mask;
 	I915_WRITE(SOFT_SCRATCH(15), val & ~msg);
 	spin_unlock(&guc->irq_lock);
+	enable_rpm_wakeref_asserts(dev_priv);
 
 	intel_guc_to_host_process_recv_msg(guc, msg);
 }