IB/mlx5: Add HW counter called rx_dct_connect

The rx_dct_connect counter shows the number of received connection
requests for the associated DCTs.

Signed-off-by: Shetu Ayalew <shetu@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Link: https://lore.kernel.org/r/01cd24cd7f591734741309921fdc01fc770d84a8.1690121941.git.leon@kernel.org


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