power: supply: cpcap-charger: Limiting charge current on Droid 4

Droid 4 has same problem as N900: it is often necessary to manually
tweak current draw from USB, for example when using thin charging cable.

Cc: Arthur Demchenkov <spinal.by@gmail.com>
Cc: Carl Philipp Klemm <philipp@uvos.xyz>
Cc: Merlijn Wajer <merlijn@wizzup.org>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Pavel Machek <pavel@ucw.cz>
[tony@atomide.com: rebased, cleaned up whitespace issues, updated comments]
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>