If secs_per_zone is corrupted due to fuzzing test, it will cause divide
zero operation when using GET_ZONE_FROM_SEG macro, so we should do more
sanity check with secs_per_zone during mount to avoid this issue.
Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>