[ofw] Patch: swap the src and dst gids to allow mad replies to return

[Sean Hefty]

>The following patch is needed in order to allow mads with grh to return
>correctly.

Is this what we want when reporting a received MAD?  Are the LIDs treated in a
similar fashion?

>+ if (p_mad_element->grh_valid) {
>+  // swap the src and dst gids to allow replys to return
>+  ib_gid_t tmp_gid;
>+  tmp_gid = p_mad_element->p_grh1->src_gid;
>+  p_mad_element->p_grh1->src_gid = p_mad_element->p_grh1->dest_gid;
>+  p_mad_element->p_grh1->dest_gid = tmp_gid;
>+ }