mlx5 PF can disable RoCE for its VFs and SFs. In such case RoCE is
marked as unsupported on those VFs/SFs.
The cited patch added an option for disable (and enable) RoCE at HCA
level. However, that commit didn't check whether RoCE is supported on
the HCA and enabled user to try and set RoCE to on.
Fix it by checking whether the HCA supports RoCE.

Fixes: fbfa97b4 ("net/mlx5: Disable roce at HCA level")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>