GitLab

* [Feature] Support ball_query with cambricon MLU backend and mlu-ops library.

* [Fix] update operator data layout setting.

* [Fix] add cxx compile option to avoid symbol conflict.

* [Fix] fix lint errors.

* [Fix] update ops.md with info of ball_query support by MLU backend.

* [Feature] Fix typo.

* [Fix] Remove print.

* [Fix] get mlu-ops from MMCV_MLU_OPS_PATH env.

* [Fix] update MMCV_MLU_OPS_PATH check logic.

* [Fix] update error info when failed to download mlu-ops.

* [Fix] check mlu-ops version matching info in mmcv.

* [Fix] revise wrong filename.

* [Fix] remove f.close and re.