anv: Do depth/stencil optimization for dynamic depth/stencil

anv: Do depth/stencil optimization for dynamic depth/stencil

When we made depth/stencil dynamic, we lost the optimization.  This is
particularly important for cases where the stencil test is enabled but
never writes anything as certain combinations with discard can cause
the stencil write (which doesn't do anything) to get moved late which
can be a measurable perf hit.  According to 028e1137e67b ("anv/pipeline:
Be smarter about depth/stencil state", it was a couple percent for DOTA2
on Broadwell back in the day.  No idea how it affects current titles.

This may also improve the depth/stncil PMA workarounds on Gen8 and Gen9
since they're now looking at optimized depth/stencil state.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17564>