lightnvm: comments on constants

It is not obvious what NVM_IO_* and NVM_BLK_T_* are used for. Make sure
to comment them appropriately as the other constants.

Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
1 file changed