ASoC: rt5659: fix wrong control register for ADC2 power

The control register for ADC L2 and R2 is RT5659_PWR_DIG_1
not RT5659_PWR_DIG_2.

Signed-off-by: Zhong An <zhongan@pinecone.net>
Signed-off-by: Bard Liao <bardliao@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>