acer-wmi: Fix WMI ID

This patch change WMI ID to upper characters. With this patch module
acer-wmi is automatically loaded when WMI ID is detected.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Tested-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>