thinkpad-acpi: Fix procfs hotkey reset command

echo "reset" > /proc/acpi/ibm/hotkey should do something non-useless,
so instead of setting it to Fn+F2, Fn+F3, Fn+F5, set it to
hotkey_recommended_mask.

It is not like it will survive for much longer, anyway.

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