power: qpnp-linear-charger: JEITA fixes

Add following fixes to support JEITA compliance:

1. Add SYSTEM TEMP LEVEL property for battery psy.
2. Fix corner cases in JEITA notification

CRs-Fixed: 654612
Change-Id: I42e88e262f196eb17789f9759fea2f0d9f42ba41
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>