PR #10875: [XLA:CPU][oneDNN][Bugfix] Fix BF16 oneDNN Layernorm
PR #10875: [XLA:CPU][oneDNN][Bugfix] Fix BF16 oneDNN Layernorm

Imported from GitHub PR https://github.com/openxla/xla/pull/10875

OneDNN expects scale and bias to be in Float32.
This PR will convert BF16/FP16 scale and weights into Float32 (similar to whats done with mkl layernorm in tensorflow [here ](https://github.com/tensorflow/tensorflow/blob/3a5a9ec33c1194f8fdec2a243714055c0118b44a/tensorflow/core/kernels/mkl/mkl_layer_norm_op.cc#L138)) , without conversion there is accuracy mismatch with oneDNN layernorm.
Copybara import of the project:

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8563d4e9fbdc6681329960c44193ed05f8a16dfd by Sachin Muradi <sachin.muradi@intel.com>:

Fix for bf16/fp16 scale bias

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e7328a3bbbe3e30caeebc27b7b0175eda9e8b5e9 by Sachin Muradi <sachin.muradi@intel.com>:

close review comments

Merging this change closes #10875

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/openxla/xla/pull/10875 from Intel-tensorflow:sachin/ln-bug-fix-bf16 e7328a3bbbe3e30caeebc27b7b0175eda9e8b5e9
