Control battery charge thresholds through the battery API and driver's
attributes.

Setting battery charging thresholds can introduce a race condition with
MACH-WX9 where two or more threads are trying to read/write values
from/to EC memory.
Signed-off-by: Ayman Bagabas <ayman.bagabas@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>