dm-zone: Use bdev_*() helper functions where applicable

Improve code readability by using bdev_is_zone_aligned() and
bdev_offset_from_zone_start() where applicable. No functionality
has been changed.

This patch is a reworked version of a patch from Pankaj Raghav.

See also https://lore.kernel.org/linux-block/20220923173618.6899-11-p.raghav@samsung.com/

.

Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>