ENGR00213722:MX6 SABRESD battery:add voltage offset sysfs

ENGR00213722:MX6 SABRESD battery:add voltage offset sysfs

interface and modify driver

1.add battery sample voltage offset sysfs interface.
2.add usb charger powersupply from max8903 UOK.
3.modify battery max coulomb data to 99% in charger full stage and
  modify battery max coulomb data to 100% in discharger stage,because
  hardware cannot support battery internal resistance and coulomb
  calculation.Battery voltage and coulomb may increase a bit in charger
  stage,so keep max coulomb data 99% in charger full stage.

Signed-off-by: Rong Dian <b38775@freescale.com>