drm/i915: Fix bounds check in intel_get_shared_dpll_id()

intel_get_shared_dpll_id(struct drm_i915_private *dev_priv,

			 struct intel_shared_dpll *pll)

{

	if (drm_WARN_ON(&dev_priv->drm, pll < dev_priv->shared_dplls ||

			pll > &dev_priv->shared_dplls[dev_priv->num_shared_dpll]))

	long pll_idx = pll - dev_priv->shared_dplls;

	if (drm_WARN_ON(&dev_priv->drm,

			pll_idx < 0 ||

			pll_idx >= dev_priv->num_shared_dpll))

		return -1;

	return (enum intel_dpll_id) (pll - dev_priv->shared_dplls);

	return pll_idx;

}

/* For ILK+ */