commit c5971456 upstream.

We only need to regenerate the sysfs files when the capacity units
change, avoid the update otherwise.

The origin of this issue is dates way back to 2.6.38:
da8aeb92
(ACPI / Battery: Update information on info notification and resume)
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Tested-by: Ralf Jung <post@ralfj.de>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>