ipmi: remove redundant initialization of bmc

The pointer bmc is being initialized and this initialized value is
never being read, so this is assignment redundant and can be removed.
Cleans up clang warning:

warning: Value stored to 'bmc' during its initialization is never read
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NCorey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmi_msghandler.c

@@ -2941,7 +2941,7 @@ static int __ipmi_bmc_register(ipmi_smi_t intf,
 			       bool guid_set, guid_t *guid, int intf_num)
 {
 	int               rv;
-	struct bmc_device *bmc = intf->bmc;
+	struct bmc_device *bmc;
 	struct bmc_device *old_bmc;
 
 	/*