anv: Drop some VK_IMAGE_TILING_OPTIMAL checks

anv: Drop some VK_IMAGE_TILING_OPTIMAL checks

The DRM format modifiers extension adds a TILING_DRM_FORMAT_MODIFIER
which will be used for modifiers so we can no longer use OPTIMAL to
indicate tiled inside the driver.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3434>