LU-3727 nfs: Fix ll_get_parent() LBUG caused by permission

LU-3727 nfs: Fix ll_get_parent() LBUG caused by permission

When ll_get_parent() is trying to get the attributes of parent
directory, EACCES will be returned if NFS daemon user does not
have the execute permission of the child directory. This patch
fixes the problem by skipping permission check for ll_get_parent().

Signed-off-by: Li Xi <lixi@ddn.com>
Change-Id: Id922d170c89519b755f69a2818d6ed53f8cc7ad9
Reviewed-on: http://review.whamcloud.com/7327
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Tested-by: Jenkins
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>