drm/i915: Introduce HAS_SAGV()

Introuce a HAS_SAGV() macro to answer the question whether
the platform in general supports SAGV. intel_has_sagv() will
keep on giving us the more specific answer whether the current
device supports SAGV or not.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230131002127.29305-2-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>