drm/i915: Rename dev_priv->gtt to dev_priv->ggtt

Refer to Global GTT consistently as GGTT, thus rename dev_priv->gtt
to dev_priv->ggtt and struct i915_gtt to struct i915_ggtt.

Fix a couple of whitespace problems while at it.

v2:
- Fix a typo in commit message.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 00c41a4..b1d6554 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1810,7 +1810,7 @@
 	struct drm_atomic_state *modeset_restore_state;
 
 	struct list_head vm_list; /* Global list of all address spaces */
-	struct i915_gtt gtt; /* VM representing the global address space */
+	struct i915_ggtt ggtt; /* VM representing the global address space */
 
 	struct i915_gem_mm mm;
 	DECLARE_HASHTABLE(mm_structs, 7);
@@ -3126,7 +3126,7 @@
 
 /* Some GGTT VM helpers */
 #define i915_obj_to_ggtt(obj) \
-	(&((struct drm_i915_private *)(obj)->base.dev->dev_private)->gtt.base)
+	(&((struct drm_i915_private *)(obj)->base.dev->dev_private)->ggtt.base)
 
 static inline struct i915_hw_ppgtt *
 i915_vm_to_ppgtt(struct i915_address_space *vm)