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: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170606133229.12439-1-ville.syrjala@linux.intel.comReviewed-by: NRodrigo Vivi <rodrigo.vivi@intel.com>