power: qpnp-linear-charger: Fix interrupt storm due to VBAT_DET irq

VBAT_DET interrupt storm is observed when battery voltage is close to
VBAT_DET threshold. Fix this by overriding VBAT_DET comparator and
disabling VBAT_DET irq as follows:

1. During charging phase:
Override VBAT_DET comparator to 0 to always force charging.

2. During discharging phase and end-of-charge:
Enable VBAT_DET based recharge (enable VBAT_DET comparator and
irq)

There are scenarios where a charger gets inserted when SOC > resume_soc
and VBAT above VBAT_DET. In this case charging does not start, which can
be annoying to the user. Fix this by always enabling charging on charger
insertion irrespective of resume_soc or VBAT_DET thresholds.

CRs-Fixed: 679886
Change-Id: I2ff481ee83a5969206e2a1456e5240b53a98353a
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>