RDMA/nldev: Expose whether RDMA monitoring is supported

RDMA/nldev: Expose whether RDMA monitoring is supported

Extend the "rdma sys" command to display whether RDMA
monitoring is supported.

RDMA monitoring is not supported in mlx4 because it does
not use the ib_device_set_netdev() API, which sends the
RDMA events.

Example output for kernel where monitoring is supported:
$ rdma sys show
netns shared privileged-qkey off monitor on copy-on-fork on

Example output for kernel where monitoring is not supported:
$ rdma sys show
netns shared privileged-qkey off monitor off copy-on-fork on

Signed-off-by: Chiara Meiohas <cmeiohas@nvidia.com>
Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
Link: https://patch.msgid.link/20240909173025.30422-8-michaelgur@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>