* optimze small N case using vec io and using rcp div
* [Ck_tile] layernorm, add param to control fastdiv; change generate codes and test pass
* [Ck_tile] fix blockSize compute in Generic2dBlockShape
* [Ck_tile]fix kfastfdiv template style
* [Ck_tile] layernorm, fix stype in review
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Co-authored-by: dummycoderfe <noplydummmycoder@163.com>