watchdog: sbc_fitpc2_wdt: fixed I/O operations order

There are fitpc2 compatible boards that hang with existent i/o
operations order. Solution is to switch between writing to data
and command ports.

Signed-off-by: Denis Turischev <denis@compulab.co.il>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>