drm/xe/xe3p_lpm: Add special check in Media GT for Main GAMCTRL

drm/xe/xe3p_lpm: Add special check in Media GT for Main GAMCTRL

For Xe3p arch some subunits of an IP may be different. The GMD_ID
register returns the Xe3p arch and dedicates the reserved field to mark
possible subunit differences. Generally this is an under-the-hood
implementation detail that drivers don't need to worry about, but the
new Main_GAMCTRL may be enabled or not depending on those.

Those reserved bits are described for Xe3p as: "If Zero, No special case
to be handled. If Non-Zero, special case to be handled by Software
agent.". That special case is defined per Arch. So if media version is
35, also check the additional reserved bits. To avoid confusion with the
usual meaning of "reserved", define them as GMD_ID_SUBIP_FLAG_MASK.

Bspec: 74201
Signed-off-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20251019-xe3p-gamctrl-v1-2-ad66d3c1908f@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>