drm: Fixup failure paths in drm_atomic_helper_set_config

I've screwed this up when removing the legacy backoff hack.

Fixes: 38b6441e ("drm/atomic-helper: Remove the backoff hack from set_config")
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170329174136.10330-1-daniel.vetter@ffwll.ch

drivers/gpu/drm/drm_atomic_helper.c

@@ -2293,10 +2293,11 @@ int drm_atomic_helper_set_config(struct drm_mode_set *set,
 	state->acquire_ctx = ctx;
 	ret = __drm_atomic_helper_set_config(set, state);
 	if (ret != 0)
-		return ret;
+		goto fail;
 
 	ret = drm_atomic_commit(state);
 
+fail:
 	drm_atomic_state_put(state);
 	return ret;
 }