[PATCH] IPMI: Add maintenance mode

Some commands and operations on a BMC can cause the BMC to "go away" for a
while.  This can cause the automatic flag processing and other things of that
nature to timeout and generate annoying logs, or possibly cause other bad
things to happen when in firmware update mode.

Add detection of those commands (cold reset, warm reset, and any firmware
command) and turns off automatic processing for 30 seconds.  It also add a
manual override either way.

Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>