freedreno/ir3: move nir finalization to after cache miss

freedreno/ir3: move nir finalization to after cache miss

In cases where every variant is a shader-cache-hit, we never need the
post-finalize round of nir opt/lowering passes.  So defer this until
the first shader-cache-miss to avoid doing pointless work.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5372>