Input: alps - fix old protocol decoding

Correct touchpad left & right keys assignments for ALPS_OLDPROTO
that were swapped. Old protocol is used on UMAX ActionBook-530T
notebook.

Signed-off-by: Yotam Medini <yotam.medini@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>