this patch export ssb_watchdog_timer_set to allow to use it in a Linux 
watchdog driver.

Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
Acked-by : Michael Buesch <mb@bu3sch.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>