The memory allocated for the slow path table flow group input structure
was not freed upon successful return, fix that.

Fixes: 1967ce6e ("net/mlx5: E-Switch, Refactor fast path FDB table creation in switchdev mode")
Signed-off-by: NRaed Salem <raeds@mellanox.com>
Reviewed-by: NOr Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>