s390/vmur: Switch over to sysfs_emit()

Per Documentation/filesystems/sysfs.rst, sysfs_emit() is preferred for
presenting attributes to user space in sysfs. Convert the left-over uses
in the char/vmur code.

Signed-off-by: Mete Durlu <[e-mail]>
Reviewed-by: Heiko Carstens <[e-mail]>
Signed-off-by: Heiko Carstens <[e-mail]>

drivers/s390/char/vmur.c

···
 	urd = urdev_get_from_cdev(to_ccwdev(dev));
 	if (!urd)
 		return -ENODEV;
-	rc = sprintf(buf, "%zu\n", urd->reclen);
+	rc = sysfs_emit(buf, "%zu\n", urd->reclen);
 	urdev_put(urd);
 	return rc;
 }