erofs: clean up zmap.c
Several trivial cleanups which aren't quite necessary to split:
- Rename lcluster load functions as well as justify full indexes
since they are typically used for global deduplication for
compressed data;
- Avoid unnecessary lines, comments for simplicity.
No logic changes.
Reviewed-by: Guo Xuenan <guoxuenan@huaweicloud.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230615064421.103178-1-hsiangkao@linux.alibaba.com