fix kunlun sharding v2 bug. Sharding v2 need inplace assign

[QingshuChen]

PR Category

Others

PR Types

Others

Description

sharding v2需要把权重inplace更新到split_param中. 当前因为缺失了assign inplace更新, fallback到cpu, 导致split_param值为0

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[runzhech]

lgtm