ACPI: thinkpad-acpi: fix regression on HKEY LID event handling

We were letting ThinkPad-specific LID events through to userspace again,
instead of dropping them.  Fix it.  We don't want to give userspace the
option of not using generic LID handling.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>