ggml-cpu: Use tiled FA for prompt-processing (llama/19012)

ggml-cpu: Use tiled FA for prompt-processing (llama/19012)

* ggml-cpu: Use tiled FA for prompt-processing

the FA performance is gimped on CPU on long contexts because it essentially uses a vector kernel. This PR adds a tiled FA for PP. Perf tuning for tile sizes done on a AMD EPYC single-socket 64-c machine.

* fix out of bounds for mask

* skip rows where there are all masks

* skip tile if mask is inf

* store mask in worksize

* check inf tile earlier