pm2301-charger: Charging LED control for pm2301

The LED Indicator feature allows indicating through a led when the
PM2301 battery charging is active. SW shall not disable this LED.

Signed-off-by: Rupesh Kumar <rupesh.kumar@stericsson.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Marcus COOPER <marcus.xm.cooper@stericsson.com>
Reviewed-by: Philippe LANGLAIS <philippe.langlais@stericsson.com>