drm/xe/vf: Don't run any save-restore RTP actions if VF

There are no RTP save-restore actions applicable for VFs on
current platforms. If any future platform will require some,
we will need to update the RTP framework to support VF_READY
or VF_ONLY actions. In the meantime, just skip all actions if
we are running as VF driver.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240619214557.905-3-michal.wajdeczko@intel.com