os/bluestore: fix crash caused by dividing by 0

In Allocator::create() => ZonedAllocator::ZonedAllocator()
num_zones is calculated by size / zone_size,
causing a crash when zone_size is set to 0

Signed-off-by: Jrchyang Yu <[email protected]>

Author: yujrchyang

src/os/bluestore/BlueStore.cc

@@ -6890,7 +6890,7 @@ int BlueStore::_create_alloc()
       cct, cct->_conf->bluestore_allocator,
       bdev->get_conventional_region_size(),
       alloc_size,
-      0, 0,
+      zone_size, 0,
       "zoned_block");
     if (!a) {
       lderr(cct) << __func__ << " failed to create " << cct->_conf->bluestore_allocator