PR #10631: [XLA:CPU][oneDNN] Minor fix in CPU bfloat16 support
PR #10631: [XLA:CPU][oneDNN] Minor fix in CPU bfloat16 support

Imported from GitHub PR https://github.com/openxla/xla/pull/10631

Align the usage of oneDNN bf16 cpu float normalization with the same guarding condition as for oneDNN rewrites in compilation step, i.e., only when oneDNN is enabled and in non-AOT mode.
Copybara import of the project:

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8166205b6491dd53dcd65e3898b4b9edfa641517 by Yimei Sun <yimei.sun@intel.com>:

[XLA:CPU][oneDNN] Minor fix in CPU bfloat16 support

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9b4f9136f1976b4432e1a60f2deb4a17c150dd3f by Yimei Sun <yimei.sun@intel.com>:

Move CpuFloatSupport reference under guard condition

Merging this change closes #10631

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/openxla/xla/pull/10631 from Intel-tensorflow:yimei/fix_cpu_bf16_support 9b4f9136f1976b4432e1a60f2deb4a17c150dd3f
