intel/blorp: Refactor the HiZ op interface

intel/blorp: Refactor the HiZ op interface

This commit does a few things:

 1) Now that BLORP can do HiZ ops on gen8+, drop the gen6 prefix.
 2) Switch parameters to uint32_t to match the rest of blorp.
 3) Take a range of layers and loop internally.

Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>