RDMA/core: Fix reported speed and width

RDMA/core: Fix reported speed and width

When the returned speed from __ethtool_get_link_ksettings() is
SPEED_UNKNOWN this will lead to reporting a wrong speed and width for
providers that uses ib_get_eth_speed(), fix that by defaulting the
netdev_speed to SPEED_1000 in case the returned value from
__ethtool_get_link_ksettings() is SPEED_UNKNOWN.

Fixes: d41861942fc5 ("IB/core: Add generic function to extract IB speed from netdev")
Link: https://lore.kernel.org/r/20200902124304.170912-1-kamalheib1@gmail.com
Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>