drm/xe: fix pat[2] programming with 2M/1G pages

Bit 7 in the leaf node is normally programmed with pat[2], however with
2M/1G pages that same bit in the PDE/PDPE also toggles 2M/1G pages. For
2M/1G entries the pat[2] is rather moved to bit 12, which is now free
given that the address must be aligned to 2M or 1G, leaving bit 7 for
toggling 2M/1G pages.

Bspec: 59510, 45038
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>