power: qpnp-qg: Add ESR estimation

Add support for online ESR (equivalent series resistance)
estimation for the battery. It is currently enabled during
charge.

The QG driver periodically (configurable) fires ESR
pulses and calculates the ESR. The ESR is qualified and
filtered before passing it to the userspace for further
processing. The processed values from userspace are
stored back into SDAM for subsequent reboots.

While at it, also add a few DT properties for ESR and update
the capacity learning default values.

Change-Id: Ic343f0d8a0109020fe384089355cfbe9a92f9a78
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>