drm/i915: fix regression after clock gating init split

During the refactoring in revision 6067aaea,
the intel_enable_clock_gating was split up into several functions that are
then called indirectly. However, which function to call was not specified for
the IS_PINEVIEW() case. This patch specifies the correct gating function.
Signed-off-by: Jason Stubbs <jasonbstubbs@gmail.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_display.c

@@ -7675,6 +7675,7 @@ static void intel_init_display(struct drm_device *dev)
 			dev_priv->display.update_wm = NULL;
 		} else
 			dev_priv->display.update_wm = pineview_update_wm;
+		dev_priv->display.init_clock_gating = gen3_init_clock_gating;
 	} else if (IS_G4X(dev)) {
 		dev_priv->display.update_wm = g4x_update_wm;
 		dev_priv->display.init_clock_gating = g4x_init_clock_gating;