ARM: SAMSUNG: Revise PM for 12-bit ADC operations

- Fixed: 12bit precision is lost at suspend/resume
- Updated: use pm_dev_ops

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>