vk: Document how depth/stencil formats work in anv_image_create()

This reverts commits

  e17ed04 * vk/image: Don't double-allocate stencil buffers
  1ee2d1c * vk/image: Teach anv_image_choose_tile_mode about WMAJOR

and instead adds a comment to describe the subtlety of how we create
images for stencil only formats.
1 file changed