tests/gem_render_copy: Adjust the tgl+ compressed buf alignments

GEN12+ the render and media compressed surface have different alignment
requiremens than ICL, so adjust that.

v2:
- Clarify a bit the comments about AUX CCS units vs. main surface tiles.
  (Ville)

Cc: Mika Kahola <mika.kahola@intel.com>
Cc: Brian Welty <brian.welty@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Brian Welty <brian.welty@intel.com>