LU-2675 mdt: refactor mdt_getattr_name_lock()

LU-2675 mdt: refactor mdt_getattr_name_lock()

In mdt_getattr_name_lock(), concentrate the cross reference handling
code into one block. Remove assertions about the remoteness of parent.
Remove some set but unused local variables in mdt_handler.c. Declare
functions static where possible. Remove the unused structures
mdt_handler and mdt_opc_slice.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I3468e200130259cf7c760bb080c1bdff9e03fd8e
Reviewed-on: http://review.whamcloud.com/9861
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>