[WATCHDOG] ipmi: add the standard watchdog timeout ioctls

Add the standard IOCTLs to the IPMI driver for setting and getting
the pretimeout.  Tested by Benoit Guillon.

Signed off by: Corey Minyard <cminyard@mvista.com>
Cc: Benoit Guillon <guillon@thalescomputers.fr>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>