drm/rockchip: cdn-dp: Fix error handling

It is likely that both 'clk_disable_unprepare()' should be called if
'pm_runtime_get_sync()' fails.

Add a new label for that, because 'err_set_rate' is not meaningful in this
case.

Add a missing call to 'pm_runtime_put()'.

Fixes: 1a0f7ed3abe2 ("drm/rockchip: cdn-dp: add cdn DP support for rk3399")

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Mark Yao <mark.yao@rock-chips.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170220070815.23096-1-christophe.jaillet@wanadoo.fr

drivers/gpu/drm/rockchip/cdn-dp-core.c

@@ -111,7 +111,7 @@ static int cdn_dp_clk_enable(struct cdn_dp_device *dp)
 	ret = pm_runtime_get_sync(dp->dev);
 	if (ret < 0) {
 		DRM_DEV_ERROR(dp->dev, "cannot get pm runtime %d\n", ret);
-		goto err_pclk;
+		goto err_pm_runtime_get;
 	}
 
 	reset_control_assert(dp->core_rst);
@@ -133,6 +133,8 @@ static int cdn_dp_clk_enable(struct cdn_dp_device *dp)
 	return 0;
 
 err_set_rate:
+	pm_runtime_put(dp->dev);
+err_pm_runtime_get:
 	clk_disable_unprepare(dp->core_clk);
 err_core_clk:
 	clk_disable_unprepare(dp->pclk);