md/raid0: fix uninitialized variable bug

If this function fails the callers expect that *private_conf is set to
an ERR_PTR() but that isn't true for the first error path where we can't
allocate "conf".  It leads to some uninitialized variable bugs.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Shaohua Li <shli@fb.com>

drivers/md/raid0.c

@@ -85,6 +85,7 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
 	struct r0conf *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
 	unsigned short blksize = 512;
 
+	*private_conf = ERR_PTR(-ENOMEM);
 	if (!conf)
 		return -ENOMEM;
 	rdev_for_each(rdev1, mddev) {