power: pm8921-charger: change ENERGY_FULL to CHARGE_FULL

Currently the reported ENERGY_FULL property reports
a value in nAh which does not comply with the power
supply class.

Fix this by changing the property to CHARGE_FULL and
changing the reported units to uAh.

Change-Id: Ib1161d3d8c4a9378eabf44f9de1eae9556d82643
Signed-off-by: David Keitel <dkeitel@codeaurora.org>