drm/i915: add helper for checking whether IRQs are enabled

Now that we use the runtime IRQ enable/disable functions in our suspend
path, we can simply check the pm._irqs_disabled flag everywhere.  So
rename it to catch the users, and add an inline for it to make the
checks clear everywhere.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index d23ba37..3f88f29 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4976,7 +4976,7 @@
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	/* Interrupts should be disabled already to avoid re-arming. */
-	WARN_ON(dev->irq_enabled && !dev_priv->pm.irqs_disabled);
+	WARN_ON(intel_irqs_enabled(dev_priv));
 
 	flush_delayed_work(&dev_priv->rps.delayed_resume_work);
 
@@ -4991,7 +4991,7 @@
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	/* Interrupts should be disabled already to avoid re-arming. */
-	WARN_ON(dev->irq_enabled && !dev_priv->pm.irqs_disabled);
+	WARN_ON(intel_irqs_enabled(dev_priv));
 
 	if (IS_IRONLAKE_M(dev)) {
 		ironlake_disable_drps(dev);
@@ -7069,5 +7069,5 @@
 			  intel_gen6_powersave_work);
 
 	dev_priv->pm.suspended = false;
-	dev_priv->pm.irqs_disabled = false;
+	dev_priv->pm._irqs_disabled = false;
 }