power_supply: Add new power supply properties CHARGE_CURRENT/VOLTAGE_MAX

There are different types of chargers avalibale like AC, Solar, USB,
etc..  Even in USB we have different types SDP/DCP/CDP/ACA and all these
chargers have different o/p ratings. For example SDP supports only 500mA
of charge current whereas AC charger can support upto 8A or more.

Similarly batteries also come with charge current and voltage ratings
and these ratings vary depending on its capacity and the technology
used.

This patch adds two new power supply properties
CONSTANT_CHARGE_CURRENT_MAX and CONSTANT_CHARGE_CURRENT_MAX.

Signed-off-by: Ramakrishna Pallala <ramakrishna.pallala@intel.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>