net/mlx5: Suppress error logging on UCTX creation

Suppress error logging that can be triggered by userspace upon DEVX UCTX
creation.

The reason that it's not suppressed today with the uid check to suppress
DEVX is that MLX5_CMD_OP_CREATE_UCTX command still doesn't have a uid as
it comes to create it..

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>