drm/i915: use dev_priv directly in gen8_ppgtt_notify_vgt

Remove dev local and use to_i915() in gen8_ppgtt_notify_vgt.

v2: use dev_priv directly for QUESTION_MACROS (Joonas Lahtinen)

Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461323365-21256-1-git-send-email-matthew.auld@intel.com

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -905,11 +905,10 @@ static int gen8_init_scratch(struct i915_address_space *vm)
 static int gen8_ppgtt_notify_vgt(struct i915_hw_ppgtt *ppgtt, bool create)
 {
 	enum vgt_g2v_type msg;
-	struct drm_device *dev = ppgtt->base.dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_private *dev_priv = to_i915(ppgtt->base.dev);
 	int i;
 
-	if (USES_FULL_48BIT_PPGTT(dev)) {
+	if (USES_FULL_48BIT_PPGTT(dev_priv)) {
 		u64 daddr = px_dma(&ppgtt->pml4);
 
 		I915_WRITE(vgtif_reg(pdp[0].lo), lower_32_bits(daddr));