i965/gen9: Set HALIGN_16 for all aux buffers

i965/gen9: Set HALIGN_16 for all aux buffers

Just like the previous patch, but for the GEN9 constraints.

v2:
bugfix: Gen9 HALIGN was being set for all miptree buffers (Chad). To address
this, move the check to where the gen8 check is, and do the appropriate
conditional there.

v3:
Remove stray whitespace introduced in v2 (Chad)
Rework comment to show AUX_CCS and AUX_MCS specifically. Remove misworded part
about gen7 (Chad).

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com> (v1)
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> (v1)
Reviewed-by: Chad Versace <chad.versace@intel.com>