trats2: add support to interactive charger

trats2: add support to interactive charger

This commit adds support to interactive charger api which means an
implementation of listed functions:
- charger_enable()  - enable the charger.Charger can be enabled
		      automatically if the device power on state
		      is triggered by USB cable connection.

- charger_type()    - this function returns device type connected
		      to usb port of device. For charger api matters
		      only positive value.

- battery_present() - check if battery is connected (DETBAT pin)

- battery_state()   - check battery charge level. Returns percent value.

- low_power_mode()  - switch SOC into low power mode which covers:
		      - disable cores: 1, 2, 3,
		      - disable SOC unused power domains,
		      - decrease CPU clock to 200 MHz

After low_power_mode() function call, device should be restarted,
which is implemented in interactive charger.

Change-Id: I7e664fab29c45c2d29dc57a2faa887d88530d8f3
Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>