RDMA/hns: Avoid setting loopback indicator when smac is same as dmac

The loopback flag will be set to 1 by the hardware when the source mac
address is same as the destination mac address. So the driver don't need
to compare them.

Fixes: d6a3627e ("RDMA/hns: Optimize wqe buffer set flow for post send")
Link: https://lore.kernel.org/r/1605526408-6936-4-git-send-email-liweihang@huawei.com


Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>