devlink: Avoid duplicate check for reload enabled flag

Reload operation is enabled or not is already checked by
devlink_reload(). Hence, remove the duplicate check from
devlink_nl_cmd_reload().

Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>