RDMA/core: Remove unused declaration rdma_resolve_ip_route()

The definition of rdma_resolve_ip_route() has been removed. Remove the
unused declaration.

Fixes: 6aaecd38 ("RDMA/core: Simplify roce_resolve_route_from_path()")
Link: https://patch.msgid.link/r/20240818055702.79547-2-zhangzekun11@huawei.com


Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>