lightnvm: pblk: assume that chunks are closed on 1.2 devices

We can't know if a block is closed or not on 1.2 devices, so assume
closed state to make sure that blocks are erased before writing.

Fixes: 32ef9412 ("lightnvm: pblk: implement get log report chunk")
Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>