drm/i915: Pass dev_priv to ilk_disable_lp_wm()

Get rid of another 'dev' usage by passing dev_priv instead.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191127190556.1574-3-ville.syrjala@linux.intel.com


Reviewed-by: José Roberto de Souza <jose.souza@intel.com>