net/mlx5e: Change enum to better reflect usage

Change MLX5E_STATE_ASYNC_EVENTS_ENABLE to
MLX5E_STATE_ASYNC_EVENTS_ENABLED since it represent a state and not an
operation.

Fixes: acff797c

 ('net/mlx5: Extend mlx5_core to support ConnectX-4 Ethernet functionality')
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>