lightnvm: export set bad block table

Bad blocks should be managed by block owners. This would be either
targets for data blocks or sysblk for system blocks.

In order to support this, export two functions: One to mark a block as
an specific type (e.g., bad block) and another to update the bad block
table on the device.

Move bad block management to rrpc.

Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>