drm/i915: Extract skl_dpll0_disable()

Make thins a bit easier to read by extracting the SKL DPLL0
disable into separate functions. We already have the enable
counterpart. Down the line this will also help make the cdclk
programming on SKL, BXT, and following platforms look rather
consistent.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1462995892-32416-9-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -5606,6 +5606,14 @@ skl_dpll0_enable(struct drm_i915_private *dev_priv, unsigned int required_vco)
 		DRM_ERROR("DPLL0 not locked\n");
 }
 
+static void
+skl_dpll0_disable(struct drm_i915_private *dev_priv)
+{
+	I915_WRITE(LCPLL1_CTL, I915_READ(LCPLL1_CTL) & ~LCPLL_PLL_ENABLE);
+	if (wait_for(!(I915_READ(LCPLL1_CTL) & LCPLL_PLL_LOCK), 1))
+		DRM_ERROR("Couldn't disable DPLL0\n");
+}
+
 static bool skl_cdclk_pcu_ready(struct drm_i915_private *dev_priv)
 {
 	int ret;
@@ -5691,10 +5699,7 @@ void skl_uninit_cdclk(struct drm_i915_private *dev_priv)
 	if (I915_READ(DBUF_CTL) & DBUF_POWER_STATE)
 		DRM_ERROR("DBuf power disable timeout\n");
 
-	/* disable DPLL0 */
-	I915_WRITE(LCPLL1_CTL, I915_READ(LCPLL1_CTL) & ~LCPLL_PLL_ENABLE);
-	if (wait_for(!(I915_READ(LCPLL1_CTL) & LCPLL_PLL_LOCK), 1))
-		DRM_ERROR("Couldn't disable DPLL0\n");
+	skl_dpll0_disable(dev_priv);
 }
 
 void skl_init_cdclk(struct drm_i915_private *dev_priv)