vol: nt_open should not create missing directories

vol: nt_open should not create missing directories

Revert the prior change that added directory creation
to nt_open().  nt_open() should fail and the caller should
create the directories.  Failure to do so results in an
incomplete tree which confuses the salvager.

Change-Id: Ieb2a05baada2531dad1869e95823fe2006bdc2c6
Reviewed-on: http://gerrit.openafs.org/3709
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>