RDMA/core: Create "issm*" device nodes only when SMI is supported

For an IB port create it's issm device node only when it has SMI
capability. In following patches mlx5 is going to support IB devices
without this cap.

Signed-off-by: Mark Zhang <markzhang@nvidia.com>
Link: https://lore.kernel.org/r/359f73c9a388d5e3ae971e40d8507888b1ba6f93.1718553901.git.leon@kernel.org


Signed-off-by: Leon Romanovsky <leonro@nvidia.com>