acer-wmi: No wifi rfkill on Lenovo machines

We have several reports which says acer-wmi is loaded on ideapads
and register rfkill for wifi which can not be unblocked.

Since ideapad-laptop also register rfkill for wifi and it works
reliably, it will be fine acer-wmi is not going to register rfkill
for wifi once VPC2004 is found.

Also put IBM0068/LEN0068 in the list. Though thinkpad_acpi has no
wifi rfkill capability, there are reports which says acer-wmi also
block wireless on Thinkpad E520/E420.

Signed-off-by: Ike Panhc <ike.pan@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>