net/mlx5e: MACsec, fix add Rx security association (SA) rule memory leak

Currently MACsec's add Rx SA flow steering (fs) rule routine
uses a spec object which is dynamically allocated and do
not free it upon leaving. The above led to a memory leak.

Fix by freeing dynamically allocated objects.

Fixes: 3b20949c ("net/mlx5e: Add MACsec RX steering rules")
Signed-off-by: Emeel Hakim <ehakim@nvidia.com>
Reviewed-by: Raed Salem <raeds@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>