power: smb135x-charger: handle DC removal in over voltage properly

In current design, we notify DC insertion when charger voltage
comes back from over voltage(OV) condition. There is another possibility
where the charger is removed from an OV state in which case DC present
state should not be notified. Add logic to handle this.

CRs-Fixed: 880466
Change-Id: I8f0f3df4e1de619ac2abf1162ac8748e2046aed1
Signed-off-by: Zhenhua Huang <zhenhuah@codeaurora.org>