Input: add driver for Fujitsu serial touchscreens

These serial touchscreens are found on some Fujitsu lifebook
P-series laptops, and the B6210. Using this requires a new
version of inputattach and doing:

 inputattach -fjt /dev/ttyS0

Big thanks to Stephen Hemminger for testing it and making it
work on his B6210 laptop.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>