drm/i915: Remove i915_gem_obj_size

Only caller is i915_gem_obj_ggtt_size which only cares about
GGTT so simplify it and implement under that name.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-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 6cf7450..32f0597 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3215,8 +3215,6 @@
 bool i915_gem_obj_bound(struct drm_i915_gem_object *o,
 			struct i915_address_space *vm);
 
-unsigned long i915_gem_obj_size(struct drm_i915_gem_object *o,
-				struct i915_address_space *vm);
 struct i915_vma *
 i915_gem_obj_to_vma(struct drm_i915_gem_object *obj,
 		    struct i915_address_space *vm);
@@ -3251,14 +3249,8 @@
 	return i915_gem_obj_ggtt_bound_view(obj, &i915_ggtt_view_normal);
 }
 
-static inline unsigned long
-i915_gem_obj_ggtt_size(struct drm_i915_gem_object *obj)
-{
-	struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
-	struct i915_ggtt *ggtt = &dev_priv->ggtt;
-
-	return i915_gem_obj_size(obj, &ggtt->base);
-}
+unsigned long
+i915_gem_obj_ggtt_size(struct drm_i915_gem_object *obj);
 
 static inline int __must_check
 i915_gem_obj_ggtt_pin(struct drm_i915_gem_object *obj,