Input: psmouse - allow drivers to use psmouse_{de,}activate

Input: psmouse - allow drivers to use psmouse_{de,}activate

BugLink: http://bugs.launchpad.net/bugs/969334

Other drivers duplicate this code; no sense in having it be private
to psmouse-base.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
(cherry picked from commit bd26f3d6fbb84f101f3e78f0591415d1c407976a)
Signed-off-by: Eric Miao <eric.miao@canonical.com>
Acked-by: Leann Ogasawara <leann.ogasawara@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>