net/mlx5e: MACsec, fix memory leak when MACsec device is deleted

When the MACsec netdevice is deleted, all related Rx/Tx HW/SW
states should be released/deallocated, however currently part
of the Rx security channel association data is not cleaned
properly, hence the memory leaks.

Fix by make sure all related Rx Sc resources are cleaned/freed,
while at it improve code by grouping release SC context in a
function so it can be used in both delete MACsec device and
delete Rx SC operations.

Fixes: 5a39816a ("net/mlx5e: Add MACsec offload SecY support")
Signed-off-by: Raed Salem <raeds@nvidia.com>
Reviewed-by: Emeel Hakim <ehakim@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>