fs/ntfs3: Check fields while reading

Added new functions index_hdr_check and index_buf_check.
Now we check all stuff for correctness while reading from disk.
Also fixed bug with stale nfs data.

Reported-by: van fantasy <g1042620637@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>