power: smb5: Add VOLTAGE_MAX_DESIGN property to usb power_supply

Modify existing VOLTAGE_MAX property of USB power_supply class to
reflect maximum voltage attainable by the current adapter settings.
Add VOLTAGE_MAX_DESIGN property to USB power_supply class to reflect
maximum voltage supported by PMIC.

Change-Id: Iab3767bb5aa0ca99b2e428a054e7b2b036aac28d
Signed-off-by: Umang Agrawal <uagrawal@codeaurora.org>