ec25519-fhmqvc: use reduced-bitlength scalar multiplication
ec25519-fhmqvc: use reduced-bitlength scalar multiplication

The values d and e will only use 128bits, so speed up the scalar multiplication
by using the new reduced-bitlength scalar multiplication functions.

This change requires the current development version of libuecc.

rlei/fastd-android,rlei/fastd-android,rlei/fastd-android,rlei/fastd-android,rlei/fastd-android