LU-1993 llite: debugging for ll_file_open LASSERT

LU-1993 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.

Test-Parameters: envdefinitions=DURATION=1800 testlist=racer
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: Ie03f706bcb32b03d94c84c5d80dae197813ebbe5
Reviewed-on: http://review.whamcloud.com/6250
Tested-by: Jenkins
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>