ASoC: wm8962: mark cache_dirty flag after software reset in pm_resume

By doing software reset of wm8962 in pm_resume, all registers which
have already been set will be reset to default value without regmap
interface be involved, thus driver need to mark cache_dirty flag,
to let regcache can be updated by regcache_sync().

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>