platform/x86: asus-wmi: Fix racy registrations

In the Linux kernel, the following vulnerability has been resolved:

platform/x86: asus-wmi: Fix racy registrations

asus_wmi_register_driver() may be called from multiple drivers concurrently, which can lead to the racy list operations, eventually corrupting the memory and hitting Oops on some ASUS machines. Also, the error handling is missing, and it forgot to unregister ACPI lps0 dev ops in the error case.

This patch covers those issues by introducing a simple mutex at acpi_wmi_register_driver() & *_unregister_driver, and adding the proper call of asus_s2idle_check_unregister() in the error path.