net/mlx5: Release FTE lock in error flow

Release the FTE lock when adding rule to the FTE has failed.

Fixes: 0fd758d6 ('net/mlx5: Don't unlock fte while still using it')
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>