power: qpnp-smbcharger: read realtime status for battery ov

Some times the battery ov status appears to not change even though the
status changes. This could be attributed to a fast battery ov pulse not
triggering the down interrupt.

Read the batt-ov status instead for reporting to the userspace.

Change-Id: I5bdb8cc6564ad37dde0e5901f0543a1c1b7b8761
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>