lightnvm: pblk: fix error handling of pblk_lines_init()

In the too many bad blocks error handling case, we should release all
the allocated resources, otherwise it will cause memory leak.

Fixes: 2deeefc0

 ("lightnvm: pblk: fail gracefully on line alloc. failure")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>