drm/i915: Use hsw_crt_get_config on BDW

Broadwell should also use hsw_crt_get_config(). Just move the
function pointer assignment to the if HAS_DDI block we already
have there.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>