power: smb358-charger: Add flexible implemention for i2c pull up supply

Flexible implemention for i2c pull up, adding an optional configuration
to indicate if pull-up source needed.

Change-Id: I1e837499ed533c4bcd5c13535952a30a7e3e6292
Signed-off-by: Zhenhua Huang <zhenhuah@codeaurora.org>