ASoC: wm8962: Remove remaining direct register cache accesses

commit 2e7ee15ced914e109a1a5b6dfcd463d846a13bd5 upstream.

Also fix return values for headphone switch updates.

Signed-off-by: Nicolin Chen <b42378@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>