lightnvm: unconverted ppa returned in get_bb_tbl

The get_bb_tbl function takes ppa as a generic address, which is
converted to the ppa device address within the device driver. When
the update_bbtbl callback is called from get_bb_tbl, the device
specific ppa is used, instead of the generic ppa.

Make sure to pass the generic ppa.

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