tests : add -INF blocks to the KQ mask in the FA tests (#16380)
* tests : add -INF blocks to the KQ mask in the FA tests
* cont : bump -INF block size to 64
Co-authored-by: Jeff Bolz <jbolz@nvidia.com>
* ggml : prevent division by zero in FA CPU op
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Co-authored-by: Jeff Bolz <jbolz@nvidia.com>