RDMA/hns: Fix uninitialized variable bug

There is a potential execution path in which variable *ret* is returned
without being properly initialized, previously.

Fix this by initializing variable *ret* to 0.

Link: https://lore.kernel.org/r/20200328023539.GA32016@embeddedor


Addresses-Coverity-ID: 1491917 ("Uninitialized scalar variable")
Fixes: 2f49de21 ("RDMA/hns: Optimize mhop get flow for multi-hop addressing")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>