LU-6486 ptlrpc: export lustre_swab_lov_mds_md

LU-6486 ptlrpc: export lustre_swab_lov_mds_md

For ppc64 clients lustre would not mount due to an Unknown
symbol error. This is due to lustre_swab_lov_mds_md not
being exported. A simple export of this function resolves
this issue.

Change-Id: Ib924045988291efbc5ac129ce58354bbc72aa7b6
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: http://review.whamcloud.com/14545
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>