Allow specifying ecc parameters in platform data

Signed-off-by: Arve Hjønnevåg <arve@android.com>
[jstultz: Tweaked commit subject & add commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>