drm/i915: Remove duplicated wm setup for vlv and chv

The code for vlv and chv wm latency/function pointer setup is
identical. Drop one of the copies.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1480354637-14209-6-git-send-email-ville.syrjala@linux.intel.com


Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>