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/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index ab1ec8d..74b0165 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2503,7 +2503,7 @@
 	/* If the FB is too big, just don't use it since fbdev is not very
 	 * important and we should probably use that space with FBC or other
 	 * features. */
-	if (size_aligned * 2 > dev_priv->gtt.stolen_usable_size)
+	if (size_aligned * 2 > dev_priv->ggtt.stolen_usable_size)
 		return false;
 
 	mutex_lock(&dev->struct_mutex);
@@ -15339,7 +15339,7 @@
 		dev->mode_config.cursor_height = MAX_CURSOR_HEIGHT;
 	}
 
-	dev->mode_config.fb_base = dev_priv->gtt.mappable_base;
+	dev->mode_config.fb_base = dev_priv->ggtt.mappable_base;
 
 	DRM_DEBUG_KMS("%d display pipe%s available.\n",
 		      INTEL_INFO(dev)->num_pipes,