This patch adds support for the coulomb counter calibration on init. We do
this by polling for now, and only add partial calibration done interrupt
support.

Then later on when we know for sure we have the calibration done interrupt
available in the device tree, we can switch to using the calibration done
interrupt.

Cc: Merlijn Wajer <merlijn@wizzup.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>