According to the IB specification, the destination qpn is allowed to be
filled into the qpc only when the qp transitions from Init to RTR, so this
code is unused.

Link: https://lore.kernel.org/r/1629985056-57004-4-git-send-email-liangwenpeng@huawei.comSigned-off-by: NWenpeng Liang <liangwenpeng@huawei.com>
Signed-off-by: NJason Gunthorpe <jgg@nvidia.com>