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/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index ef047bc..ed0b5fc 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1161,7 +1161,7 @@
 	unsigned long timeout_expire;
 	int ret;
 
-	WARN(dev_priv->pm.irqs_disabled, "IRQs disabled\n");
+	WARN(!intel_irqs_enabled(dev_priv), "IRQs disabled");
 
 	if (i915_seqno_passed(ring->get_seqno(ring, true), seqno))
 		return 0;