fs/ntfs3: Fix warning in ni_fiemap

Use local runs_tree instead of cached. This way excludes rw_semaphore lock.

Reported-by:  <syzbot+1c25748a40fe79b8a119@syzkaller.appspotmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>