Fix sparse warning:

drivers/char/ipmi/ipmi_msghandler.c:635:20: warning:
 symbol 'ipmi_interfaces_srcu' was not declared. Should it be static?
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Message-Id: <20190320133505.21984-1-yuehaibing@huawei.com>
Signed-off-by: NCorey Minyard <cminyard@mvista.com>