drm/i915: Fix fastboot scalers for skylake.

The scaler_id in intel_pipe_config_compare should not be checked
when adjusting in intel_pipe_config_compare. The hw scaler id may
be changed in intel_update_pipe_config.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>