power: smb358-charger: Add charger inhibit interface

The charger inhibit option prevents battery charging upon
insertion of charger when battery voltage is above the
programmed inhibit threshold.

Change-Id: Iaa9fd7e897f4eca3bdf8a060f15a5a181f7eb888
Signed-off-by: Zhenhua Huang <zhenhuah@codeaurora.org>