Input: psmouse-smbus - allow to control psmouse_deactivate

This seems to be Synaptics specific, as some Elan touchpads are not
correctly switching to SMBus if we call deactivate before switching to
SMBus on cold boot and on resume.

Tested with the T480s

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: KT Liao <kt.liao@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>