block: Remove blk_alloc_zone_bitmap()

Remove the helper function blk_alloc_zone_bitmap() and replace its
single call site with a call to bitmap_alloc(). To be consistent with
this change, use bitmap_free() to free a disk convnetional zone bitmap.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240704052816.623865-6-dlemoal@kernel.org


Signed-off-by: Jens Axboe <axboe@kernel.dk>