iris: Enable HiZ for non-8x4 aligned miplevels on Icelake and later

8x4 alignment was absolutely required prior to Gfx8, and while some
things were relaxed on Gfx8-9, Nanley's experiments in issue #3788
indicated that there were still issues on those platforms.

It appears that the restrictions were relaxed on Icelake and
non-8x4 aligned HiZ "should" work on Gfx11+.

Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4674>