drm/i915: Always use INTEL_INFO() to access the device_info structure

If we make sure that all the dev_priv->info usages are wrapped by
INTEL_INFO(), we can easily modify the ->info field to be structure and
not a pointer while keeping the const protection in the INTEL_INFO()
macro.

v2: Rebased onto latest drm-nightly

Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 8f579bc..d4defd8 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2276,7 +2276,7 @@
 				     PIPE_VBLANK_INTERRUPT_ENABLE);
 
 	/* maintain vblank delivery even in deep C-states */
-	if (dev_priv->info->gen == 3)
+	if (INTEL_INFO(dev)->gen == 3)
 		I915_WRITE(INSTPM, _MASKED_BIT_DISABLE(INSTPM_AGPBUSY_DIS));
 	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
 
@@ -2341,7 +2341,7 @@
 	unsigned long irqflags;
 
 	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
-	if (dev_priv->info->gen == 3)
+	if (INTEL_INFO(dev)->gen == 3)
 		I915_WRITE(INSTPM, _MASKED_BIT_ENABLE(INSTPM_AGPBUSY_DIS));
 
 	i915_disable_pipestat(dev_priv, pipe,