hwmon: (ibmpex.c) fix NULL dereference

Don't dereference "data" when we know for sure it's NULL.

Spotted by the Coverity checker.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>

drivers/hwmon/ibmpex.c

@@ -457,7 +457,7 @@ static void ibmpex_register_bmc(int iface, struct device *dev)
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data) {
 		printk(KERN_ERR DRVNAME ": Insufficient memory for BMC "
-		       "interface %d.\n", data->interface);
+		       "interface.\n");
 		return;
 	}