power: smb23x-charger: Add SMB23X charger driver

SMB23x is a linear charger capable of supporting 1.5 ampere maximum
input current which including 1 ampere maximum battery charging current.

Add the driver to support it. This driver allows to control the charging
enable/disable and other charging configurations, such as charging
current, termination current, etc. It also supports to detect the VBUS
detection/notification and other battery status updating via
power_supply framework.

Change-Id: I89c6b3c019a9598f1b91ff6d09de92817ff4e1bb
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>