char/ipmi: fix spelling mistake "receieved_messages" -> "received_messages"

There is a spelling mistake in the documentation. Fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Message-Id: <20190418101502.9748-1-colin.king@canonical.com>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Corey Minyard <cminyard@mvista.com>