staging/lustre/target: move OUT to the unified target code

- Move OUT handler to the unified target code, so it can be
  used by both MDS and OST.

Lustre-change: http://review.whamcloud.com/6763
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3467


Signed-off-by: Mikhail Pershin <mike.pershin@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
[pick client side of change. target is mostly server side code -- PengTao]
Signed-off-by: Peng Tao <bergwolf@gmail.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>