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_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 6627bbe..394e525 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -945,7 +945,7 @@
 		else if (to_i915(dev)->mm.aliasing_ppgtt)
 			args->value = to_i915(dev)->mm.aliasing_ppgtt->base.total;
 		else
-			args->value = to_i915(dev)->gtt.base.total;
+			args->value = to_i915(dev)->ggtt.base.total;
 		break;
 	default:
 		ret = -EINVAL;