drm/xe: Move helper macros to separate header

The macros to handle the RTP tables are very scary, but shouldn't be
used outside of the header adding the infra. Move it to a separate
header and make sure it's only included when it can be.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20230427223256.1432787-11-lucas.demarchi@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>