NTFS: Change ntfs_cluster_free() to require a write locked runlist on entry

NTFS: Change ntfs_cluster_free() to require a write locked runlist on entry
      since we otherwise get into a lock reversal deadlock if a read locked
      runlist is passed in. In the process also change it to take an ntfs
      inode instead of a vfs inode as parameter.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>