arm:trats:pmic: Support for charging battery at Samsung's TRATS board

The battery connected to Samsung's Trats development board is now
charged when voltage drops below threshold.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>