freedreno: switch to layout helper

freedreno: switch to layout helper

The slices table and most of the other layout fields in the
freedreno_resource moves into fdl_layout.

v2: Changes by anholt to not have duplicate fields, which was introducing
    a surprising behavior change in resource layout (using the
    level_linear helper before the setup of the shadowed fields)

Reviewed-by: Eric Anholt <eric@anholt.net>
Acked-by: Rob Clark <robdclark@chromium.org>