power: smb-lib: Modify usb max voltage reflected for QC 3.0 charger

Modify usb VOLTAGE_MAX property's reporting function to add support
for QC 3.0 chargers to reflect maximum VBUS voltage that can be attained
by QC3.0 chargers.

Change-Id: I45c15b4d8daab6eeec5c0bc5b0c19c4baa4ca15f
Signed-off-by: Umang Agrawal <uagrawal@codeaurora.org>