ASoC: wm_hubs: Enable line out VMID buffer for single ended line outputs

commit 77231abe upstream.

For optimal performance the single ended line outputs require that the
line output VMID buffer be enabled.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>