thinkpad-acpi: recognize Lenovo as version string in newer V-series BIOS

The newer V series bios reports product version as 'Lenovo'
instead of 'ThinkPad'. Recoginze this new string so that
the module can load.

Signed-off-by: Manoj Iyer <manoj.iyer@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Tested-by: James Ferguson <james.ferguson@canonical.com>
Tested-by: Dennis Chua <dennis.chua@canonical.com>
Tested-by: Ike Pan <ike.pan@canonical.com>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>