[PATCH] nvme-core: remove head->effects to fix use-after-free

[Randy Jennings]

>> It doesn't make sense for effects logs to be different per-controller
>> for the same shared namespace. The spec doesn't seem to explicitly
>> prevent that, but hints that all hosts should be seeing the same thing
>> no matter which controller they're connected to:
>
> Also agreed as already indicated in the past mail.

Yuanyuan Zhong already pointed out a situation where the commands
supported portion of the log page could be different.  When upgrading
the subsystem, some controllers may be upgraded sooner than others.
The upgrade could support new commands.

However, I would be surprised if the effects would be different for
currently supported commands, unless a controller was not reporting
effects before and starts reporting them.

Sincerely,
Randy Jennings