drm/xe/pat: Differentiate between primary and media for PTA

drm/xe/pat: Differentiate between primary and media for PTA

Differently from currently supported platforms, in upcoming changes we
will need to have different PAT entries for PTA based on the GT type. As
such, let's prepare the code to support that by having two separate
PTA-specific members in the pat struct, one for each type of GT.

While at it, also fix the kerneldoc for pat_ats.

Co-developed-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patch.msgid.link/20260206-nvl-p-upstreaming-v3-3-636e1ad32688@intel.com
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>