[PATCH 1/2] Add 'gen-dhchap-key' command

[Sagi Grimberg]

> Yee... it won't be long until we'll hear complaints on this one.
> I think we need to have some simple format like:
> <default>:<def_hostkey>
> <subsystem1>:<hostkey1>
> <subsystem2>:<hostkey2>
> ...
> 
> And we will need /etc/nvme/subsyskey in the same format:
> <default>:<def_subsyskey>
> <subsystem1>:<subsyskey1>
> <subsystem2>:<subsyskey2>
> ...
> 
> And ideally we also have a way for nvme-cli to populate it in this
> format (or some helper script for it).
> 
>> So would just stick with the simple case, and leave this as an 
>> exercise to the reader.
> 
> Don't know if that is good enough...
> What do others think?

Also, if we expand the format later, we may introduce a pain when
updating nvme-cli...