Simplify the const time lookup in ECC scalar mul
Simplify the const time lookup in ECC scalar mul

Code is easier to understand and it may let the CPU interleave the
loads and logical ops better. Slightly faster on my machine.

webmaster128/botan,webmaster128/botan,randombit/botan,randombit/botan,webmaster128/botan,randombit/botan,webmaster128/botan,randombit/botan,randombit/botan,webmaster128/botan