Aarch64: Improve codegen in SVE exp and users, and update expf_inline

Aarch64: Improve codegen in SVE exp and users, and update expf_inline

Use unpredicted muls, and improve memory access.
7%, 3% and 1% improvement in throughput microbenchmark on Neoverse V1,
for exp, exp2 and cosh respectively.

Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>
(cherry picked from commit c0ff447edf19bd4630fe79adf5e8b896405b059f)