nvme_rdma_ibv_send_wr_init() was only called in one place, so just move
its contents into nvme_rdma_qpair_submit_request() since it allows
simplification of the code:
- req was always NULL, so remove the code that used req entirely.
- wr and sg_list are never NULL, so remove the checks for those.
Change-Id: I12a4f3502219d3681607686945e343f6808c0d2f
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>