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_display.c b/drivers/gpu/drm/i915/intel_display.c
index 06566d6..1cdd1c1 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7341,7 +7341,7 @@
 	 * gen-specific and since we only disable LCPLL after we fully disable
 	 * the interrupts, the check below should be enough.
 	 */
-	WARN(!dev_priv->pm.irqs_disabled, "IRQs enabled\n");
+	WARN(intel_irqs_enabled(dev_priv), "IRQs enabled\n");
 }
 
 static uint32_t hsw_read_dcomp(struct drm_i915_private *dev_priv)