lightnvm: add 2.0 geometry identification

Implement the geometry data structures for 2.0 and enable a drive
to be identified as one, including exposing the appropriate 2.0
sysfs entries.

Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>