ACPICA: disable _BIF warning

A generic work-around from ACPICA is in the queue,
but since Linux has a work-around in its battery
driver, we can disable this warning now.

Allow _BIF method to return an Package with Buffer elements

http://bugzilla.kernel.org/show_bug.cgi?id=11822

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>