Remove ECDSA nonce padding kludge

Remove ECDSA nonce padding kludge

This was a workaround due to the historically non-constant time scalar
multiplication in the EC code. Since Brumley and Tuveri implemented the
Montgomery ladder, this is no longer useful and should have been removed
a long time ago, as it now does more harm than good.

Keep the preallocations as they still help hiding some timing info.

ok jsing