power: qpnp-charger: add sysfs access to warm/cool thresholds

Some userspace applications monitor charging closely and need to be able
to change the thresholds of the warm and cool JEITA temperature zones.

Add POWER_SUPPLY_PROP_WARM_TEMP and POWER_SUPPLY_PROP_COOL_TEMP support
to the charger driver and make the property writable via the power
supply framework.

Once a new temperature is written to the sysfs node the charger driver
will configure the jeita thresholds dependent on which zone the
battery is currently in and reconfigure the adc notification parameters.

CRs-Fixed: 494223
Change-Id: Ib969deefbed60fd33adbe7823fd02d89410de9c2
Signed-off-by: David Keitel <dkeitel@codeaurora.org>