RDMA/cma: Always set static rate to 0 for RoCE

RDMA/cma: Always set static rate to 0 for RoCE

Set static rate to 0 as it should be discovered by path query and
has no meaning for RoCE.
This also avoid of using the rtnl lock and ethtool API, which is
a bottleneck when try to setup many rdma-cm connections at the same
time, especially with multiple processes.

Fixes: 3c86aa70bf67 ("RDMA/cm: Add RDMA CM support for IBoE devices")
Signed-off-by: Mark Zhang <markzhang@nvidia.com>
Link: https://lore.kernel.org/r/f72a4f8b667b803aee9fa794069f61afb5839ce4.1685960567.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leon@kernel.org>