ipmi:ipmb: Fix a vague comment and a typo

Sending an IPMI response message gets a reponse to the response, but the
comment saying that just said "response response", which is hard to
understand.  Also fix an obvious typo.

Reported-by: Shaomin Deng <dengshaomin@cdjrlc.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>