tu: Move our image layout into a freedreno_layout struct.

This lets us start using some of the fdl_* helpers and have more obviously
matching code between gallium and turnip.  We can't yet use the fdl_* UBWC
helpers, since the gallium driver doesn't do UBWC mipmaps (which I'm
working on in another branch).

Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
6 files changed