power: smb1360: Add DT properties to configure FG parameters

Add 3 DT properties to configure the FG parameters

Cutoff Voltage: System voltage at which FG reports SOC = 0
FG Iterm: Termination current at which FG reports SOC = 100
FG Ibatt Standby: Standby current to adapt SOC at cutoff-voltage
at low temperatures.

Change-Id: I60723b19eb6ab7a49fb54b199bf31a8ffde2e5d4
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>