ublk zoned takes 16 bytes in each request pdu just for handling REPORT_ZONE
operation, this way does waste memory since request pdu is allocated
statically.

Store the transient zone report data into one global xarray, and remove
it after the report zone request is completed. This way is reasonable
since report zone is run in slow code path.

Fixes: 29802d7c ("ublk: enable zoned storage support")
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20240812013624.587587-1-ming.lei@redhat.comSigned-off-by: Jens Axboe <axboe@kernel.dk>