LU-4045 mdd: use same attr to declare setattr

LU-4045 mdd: use same attr to declare setattr

in mdd_attr_set, different lu_attr ("la" and "la_copy") is used
for declaring "setattr" and the "setattr" itself, the "LA_MODE"
could be added to "la_copy" by "mdd_fix_attr" in some case and
cause the "setxattr" in "mdd_attr_set_internal" is processed
without declaration.

Change-Id: Ic4441e0c72e8d8209d8f5e60f71ab09dc7987163
Signed-off-by: Hongchao Zhang <hongchao.zhang@intel.com>
Reviewed-on: http://review.whamcloud.com/14566
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: wangdi <di.wang@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>