drm/i915: Disable LTTPR detection on GLK once again

The glk display version change is causing us to again attempt
LTTPR detection on glk. We must not do tha since glk doesn't
have a long enough AUX timeout. Restore the correct logic to
skip the detection.

Cc: Matt Roper <matthew.d.roper@intel.com>
Fixes: 2b5a4562 ("drm/i915/display: Simplify GLK display version tests")
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210412054607.18133-4-ville.syrjala@linux.intel.com