LU-3974 llite: use new struct dir_context

LU-3974 llite: use new struct dir_context

The readdir and nfs code over time has added more
parameters to be passed to be processed. For the 3.11
kernel a new struct dir_context was introduced to
minimize the impact of future expansion. This patch
addresses this change.

Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: Ib42bf8cb06635a2a64e63b294d79e66ac82a1a5b
Reviewed-on: http://review.whamcloud.com/7747
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Peng Tao <bergwolf@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>