[cpu] Use expf() instead of exp
[cpu] Use expf() instead of exp


Former-commit-id: db704a89bb919e6a616abedfde501079a6b53ee7
rbaghdadi/pencil-benchmark,pencil-language/pencil-benchmark,dividiti/pencil-benchmark,rbaghdadi/pencil-benchmark,dividiti/pencil-benchmark,dividiti/pencil-benchmark,pencil-language/pencil-benchmark,pencil-language/pencil-benchmark,rbaghdadi/pencil-benchmark