LU-3537 mdt: allow cross-MDT rename and link

LU-3537 mdt: allow cross-MDT rename and link

Remove checks for cross-MDT operation, so cross-MDT
rename and link will be allowed.

Remove obsolete locality parameters in MDT lock API after all of
cross-MDT operations are allowed.

Change-Id: I29874d929f98593d00f5cbd836c7ce681d51add7
Signed-off-by: Wang Di <di.wang@intel.com>
Reviewed-on: http://review.whamcloud.com/12282
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>