ASoC: codecs: wm8753: Fix register cache incoherency

The multi-component patch(commit f0fba2a) moved the allocation of the
register cache from the driver to the ASoC core. Most drivers where adjusted to
this, but the wm8753 driver still uses its own register cache for its
private functions, while functions from the ASoC core use the generic cache.
Furthermore the generic cache uses zero-based numbering while the wm8753 cache
uses one-based numbering.
Thus we end up with two from each other incoherent caches, which leads to undefined
behaviour and crashes.
This patch fixes the issue by changing the wm8753 driver to use the generic
register cache in its private functions.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>