staging: lustre: llite: debugging for ll_file_open LASSERT

Add debugging for LASSERTF(it_disposition(it, DISP_ENQ_OPEN_REF)
in ll_file_open(), since this is a rarely hit failure under racer,
and it would be useful to get more information if this is hit
again.  Print the full intent disposition, as well as the status,
in case Oleg's earlier comment about bailing out on any error is
actually the case here.

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-1993
Reviewed-on: http://review.whamcloud.com/6250


Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>