ipmi: don't grab locks in run-to-completion mode

This patch prevents deadlocks in IPMI panic handler caused by msg_lock
in smi_info structure and waiting_msgs_lock in ipmi_smi structure.

[cminyard@mvista.com: remove unnecessary memory barriers]
Signed-off-by: Konstantin Baydarov <kbaidarov@ru.mvista.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>