sbin/nvmecontrol didn't support Get/Set Feature yet,
I am planing implement these commands.
here is draft version. only implement Get Feature
* Add some feature definition for some features.`sys/dev/nvme/nvme.h`
I am not sure if I am doing the right direction,* Borrow some code from `sys/dev/nvme/nvme_qpair.c`, maybe make it common later?
Please review at your convenience and give some feedback.