net/mlx5: E-Switch, free flow_group_in after creating the restore table

We allocate a temporary memory but forget to free it.

Fixes: 11b717d6

 ("net/mlx5: E-Switch, Get reg_c0 value on CQE")
Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>