patch: make SD images for arm64 boards at same release.sh

[YAMAMOTO Shigeru]

>>>>> "Mark" == Mark Linimon <linimon at lonesome.com> writes:
Mark> Would it be acceptable if I opened a review on Phabricator pointing to
Mark> these changes so that they do not get lost?

I add a review at
https://reviews.freebsd.org/D19380

Thanks,
---
YAMAMOTO Shigeru <shigeru at os-hackers.jp>