power: qpnp-smbcharger: Improve battery status notification

Currently we're updating chg_done_batt_full flag based on the
charge inhibit and charging complete interrupts. This flag is
used to indicate the battery status. However, we've to
manipulate this flag based on the events like charger insertion
or removal.
Instead of doing that, we can check the INT_RT_STS to determine
the charge inhibit or charging complete status. Based on that,
notify the battery status properly.

CRs-Fixed: 723434
Change-Id: I9b73d050b8019832b2744a126ad6dc603de31247
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>