ASoC: regulator notifier registration should be managed

Regulator notifiers, that were registered during codec driver probing,
must be unregistered during driver release, or device managed versions
have to be used. This patch fixes codec drivers, that weren't explicitly
unregistering notifiers and simplifies those, that did that manually.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>