generic: drop test 472

generic: drop test 472

From Goldwyn Rodrigues <rgoldwyn@suse.de>:

   "From earlier discussions, In between errors of a direct I/O cannot
   be handled correctly and may need a lot of tracking that it is not
   worth performing.

   It would be better to drop this test case and add in the documentation
   that a direct I/O error could mean that the write() may or may not have
   occurred and underlying data may be inconsistent."

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>