scd: Fix varargs call for 64-bit arch on ECC keys

[NIIBE Yutaka]

On 01/28/2015 12:47 AM, Werner Koch wrote:
> On Tue, 27 Jan 2015 13:05, gniibe at fsij.org said:
> 
>> Meanwhile, here is updated patch.  OK to commit?
> 
> Yep.

Thanks.  Pushed.
--