Fix typo in introduced in f88d9684

[baum]

Fix typo in config parameter name introduced in f88d968

[gbregman]

@baum
the multi gateway test source contains:

    pool = config.get("ceph", "pool")
    enable_discovery_controller = config.getboolean_with_default("gateway", "enable_discovery_controller", False)
    if not enable_discovery_controller:
         num_subsystems -= 1

But, the enable_discovery_controller parameter was removed from ceph-nvmeof.conf and is no longer used. You need to adjust the above code to the new logic.

[gbregman]

multi gateway test needs to be adjusted for new logic