i965/gen6: Force tile alignment for each stencil/hiz LOD

i965/gen6: Force tile alignment for each stencil/hiz LOD

Gen6 doesn't support multiple miplevels for hiz and stencil.

Therefore, we must point to the LOD directly during rendering.

But, we also have removed the tile offsets from normal depth surfaces,
so we need to align each LOD to a tile boundary for hiz and stencil.

v3:
 * Use new array_layout enum

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>