ASoC: wm8971: Use system_power_efficient_wq instead of custom workqueue
The delayed work used by the wm8971 driver to manage the caps charging
doesn't have any special requirements that would justify using a custom
workqueue, just use the generic system_power_efficient_wq instead.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com> Signed-off-by: Mark Brown <broonie@kernel.org>