Revert "[mkldnn_matmul] enable mkldnn matmul for aarch64 bf16 devices (#83671)"
This reverts commit f21e77d9a64b39bb9feb9946d912b7b4952430d6.
Reverted https://github.com/pytorch/pytorch/pull/83671 on behalf of https://github.com/dagitses due to breaking meta internal builds where cpuinfo_has_arm_bf16 is not defined
