Replace existing setter/getters with generated ones

[igaw]

With #54 done, the infrastructure to generate setters/getters are there. Now we should start replacing the existing once with generated ones. Track the effort here.

[igaw]

linux-nvme/nvme-cli#2956

[igaw]

The code generator is merged. Though it might make sense to run code generator by hand and check in the code into the code base. It's not that we add a lot of fields all the time.