RDMA/mlx5: Raise async event on device speed change

RDMA/mlx5: Raise async event on device speed change

Raise IB_EVENT_DEVICE_SPEED_CHANGE whenever the speed of one of the
device's ports changes. Usually all ports of the device changes
together.

This ensures user applications and upper-layer software are immediately
notified when bandwidth changes, improving traffic management in dynamic
environments. This is especially useful for vports which are part of a
LAG configuration, to know if the effective speed of the LAG was
changed.

Signed-off-by: Or Har-Toov <ohartoov@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Edward Srouji <edwards@nvidia.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>