### What this PR does / why we need it? Use group_list[0] to replace group_diff[0] in function "cumsum_group_list" (moe_mlp.py). The purpose is to modify it to the correct logic of converting cumsum to count. ### Does this PR introduce _any_ user-facing change? No Signed-off-by: tanqingshan (A) <50050625@china.huawei.com> Co-authored-by: tanqingshan (A) <50050625@china.huawei.com>