power: rk818: support rk818 battery driver

power: rk818: support rk818 battery driver

Update version to v7.0, main features:
    1. new algorithm which is independent of time calculation in almost case,
    2. remove charger detect to driver: rk818-charger.c;
    3. save algorithm calculation rest value for next system power on calculation;
    4. recognize system halt and reset dsoc as rsoc;
    5. support hardware sample resistor selected as 10mR or 20mR;
    6. optimize zero algorithm to make discharge figure more smooth;
    7. fix some logic bugs.

Change-Id: I789d070693ac16102ecbe813d878a2a3c256c030
Signed-off-by: Jianhong Chen <chenjh@rock-chips.com>