ipmi:bt-bmc: Fix some format issue of the code

Fix some format issue of the code in bt-bmc.c
Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
Signed-off-by: Shengju Zhang <zhangshengju@cmss.chinamobile.com>
Message-Id: <20200414141814.19048-1-tangbin@cmss.chinamobile.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>