ASoC: wm8962: set ALC2 as non-volatile register

ASoC: wm8962: set ALC2 as non-volatile register

Previously ALC2 register is set as a volatile register, declare
it as one of ALC Coefficients register together with other non-volatile
registers will cause issue, in case wm8962 has enter suspend mode,
and cache_only flag is set, any attempt to read from ALC2 will fail.

Because the 5 status bits in ALC2 aren't used anywhere nor are useful
to end user, so this patch removes ALC2 register from volatile
register list to make ALC2 be possible to be accessed when cache_only
flag is set.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>