Move the DDL precision handling into vlv_compute_drain_latency() so the
callers don't have to duplicate the same code to deal with it.
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>