The actual GMCH_CRTL lives in the host bridge aka. device 0,
but device 2 has a read-only mirror on i85x/i865+. Document
that fact.
Also remove the ancient tales about where the defines are used.
Those haven't been true in a long time.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20251208182637.334-20-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>