anv/cmd_buffer: Enable rendering to HiZ

anv/cmd_buffer: Enable rendering to HiZ

Nanley Chery:
(rebase)
 - Resolve conflicts with new anv_batch_emit macro
(amend)
 - Handle a QPitch TODO
 - Emit 3DSTATE_HIER_DEPTH_BUFFER on pre-BDW systems
 - Only use HiZ for single-subpass renderpasses
 - Emit the HiZ instruction before the stencil instruction to follow the
   optimized clear sequence specified in the PRMs
 - Don't modify clear params
 - Enable resolves when a HiZ buffer is used to ensure depth buffer validity

Provides an FPS increase of ~15% on the Sascha triangle and multisampling
demos.

Signed-off-by: Nanley Chery <nanley.g.chery@intel.com>
Reviewed-by: Chad Versace <chadversary@chromium.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>