btrfs: zoned: use vcalloc instead of for vzalloc in btrfs_get_dev_zone_info

Use vcalloc that checks potential multiplication overflows.  The changes
were done using Coccinelle semantic patch.

Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>