intel/isl: Allow multisampling with ISL_FORMAT_HiZ

intel/isl: Allow multisampling with ISL_FORMAT_HiZ

HiZ buffers can be multisampled and, on Broadwell and earlier, simply using
interleaved multisampling with a compression block size of 8x4 samples
yields the correct HiZ surface size calculations.  Unfortunately,
choose_msaa_layout was rejecting multisampled HiZ buffers because of format
checks.  Now that we have a simple helper for determining if a format
supports multisampling, that's an easy enough issue to fix.

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