LU-6486 ptlrpc: export lustre_swab_lmv_mds_md

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

Change-Id: I8db142e91f376fa0727b9de774ae0ca1cb0d9b5a
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: http://review.whamcloud.com/15159
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>