platform/x86: asus-wmi: Support laptops where the first battery is named BATT

The WMI method to set the charge threshold does not provide a
way to specific a battery, so we assume it is the first/primary
battery (by checking if the name is BAT0).
On some newer ASUS laptops (Zenbook UM431DA) though, the
primary/first battery isn't named BAT0 but BATT, so we need
to support that case.

Fixes: 7973353e

 ("platform/x86: asus-wmi: Refactor charge threshold to use the battery hooking API")
Cc: stable@vger.kernel.org
Signed-off-by: Kristian Klausen <kristian@klausen.dk>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>