wined3d: Get rid of the buffer_object_size field from struct wined3d_buffer.

dlls/wined3d/buffer.c

@@ -189,7 +189,6 @@ static void buffer_create_buffer_object(struct wined3d_buffer *This, struct wine
         goto fail;
     }
 
-    This->buffer_object_size = This->resource.size;
     This->buffer_object_usage = gl_usage;
 
     if (This->flags & WINED3D_BUFFER_DOUBLEBUFFER)

dlls/wined3d/wined3d_private.h

@@ -2552,7 +2552,6 @@ struct wined3d_buffer
     GLuint buffer_object;
     GLenum buffer_object_usage;
     GLenum buffer_type_hint;
-    UINT buffer_object_size;
     DWORD flags;
 
     struct wined3d_map_range *maps;