ipmi: Fix some kernel-doc warnings

The current code provokes some kernel-doc warnings:
	drivers/char/ipmi/ipmi_msghandler.c:618: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst

Signed-off-by: Bo Liu <liubo03@inspur.com>
Message-Id: <20221025060436.4372-1-liubo03@inspur.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>