ipmi: When handling send message responses, don't process the message

A chunk was dropped when the code handling send messages was rewritten.
Those messages shouldn't be processed normally, they are just an
indication that the message was successfully sent and the timers should
be started for the real response that should be coming later.

Add back in the missing chunk to just discard the message and go on.

Fixes: 059747c2 ("ipmi: Add support for IPMB direct messages")
Reported-by: Joe Wiese <jwiese@rackspace.com>
Cc: stable@vger.kernel.org # v5.16+
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Tested-by: Joe Wiese <jwiese@rackspace.com>