ASoC: rt5659: fix wrong bit define for ADC L2 power.

RT5659_PWR_ADC_L2_BIT should be 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>