LU-5329 mgs: Remove nibtbl swab code for 2.2 clients

LU-5329 mgs: Remove nibtbl swab code for 2.2 clients

Remove obsolete code that allows compatibility with
Lustre 2.2 clients.

Due to a bug, Lustre 2.2 clients always swab nidtbl
entries even if the server and client are using the
same endian. The fix was to allow the servers to do
the swabbing for the client.

Now, clients will do the swabbing.

Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: I420ca986c0a68343be07272bb419cbdb1cebf148
Reviewed-on: http://review.whamcloud.com/12010
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>