LU-8056 xattr: update server code for POSIX xattr rename

LU-8056 xattr: update server code for POSIX xattr rename

Enabling ZFS server support for linux 4.5 kernels showed
that the POSIX_ACL_XATTR_{ACCESS,DEFAULT} change to
XATTR_NAME_POSIX_ACL_{ACCESS,DEFAULT} impacts the server
side code as well. Update server side for this name change.

Change-Id: Ieeef8c047177cd55ca87b04dfdacd59d343b0078
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: http://review.whamcloud.com/21454
Tested-by: Jenkins
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Frank Zago <fzago@cray.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>