toshiba-wmi: Fix loading the driver on non Toshiba laptops
Bug 150611 uncovered that the WMI ID used by the toshiba-wmi driver
is not Toshiba specific, and as such, the driver was being loaded
on non Toshiba laptops too.
This patch adds a DMI matching list checking for TOSHIBA as the
vendor, refusing to load if it is not.
Also the WMI GUID was renamed, dropping the TOSHIBA_ prefix, to
better reflect that such GUID is not a Toshiba specific one.