power: smb135x-charger: add ov interrupts for insertion

The current driver indicates usb removal on a USB OV event.
Also need to notify usb insertion when USB is back to normal.

CRs-Fixed: 819287
Change-Id: Ie012cac647f506754fabfc76e03f546fc473894e
Signed-off-by: Zhenhua Huang <zhenhuah@codeaurora.org>