ACPI: thinkpad-acpi: issue input events for tablet swivel events

Issue EV_SW SW_TABLET_MODE events for HKEY events 0x5009 and 0x500A on the
X41t/X60t/X61t.  As usual, we suppress the HKEY events on the netlink
interface to avoid sending duplicate events to userspace.

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