Restore the lost has_fbc flag for mobile ILK.

Cc: Carlos Santa <carlos.santa@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Fixes: a1323380 ("drm/i915: Introduce GEN5_FEATURES for device info")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170606133229.12439-1-ville.syrjala@linux.intel.comReviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
(cherry picked from commit c2d1a0ce)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>