drm/i915: Pass around dev_priv in vlv wm functions

Passing dev_priv instead of dev is the future. Let's make the vlv/chv wm
functions respect that idea.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1480354637-14209-9-git-send-email-ville.syrjala@linux.intel.com


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