Put the pine64 root filesystem on teh correct partition.

The Pine64 root filesystem was incorrectly created directly on the MBR
partition. This can cause the loader to get confused when loading the
kernel from this filesystem.

The loader will see this as a small partition meaning later checks to
ensure it doesn't read past the end of the disk incorrectly report a
failure. This seems to work mostly by accident with the released images as
they are smaller than the reported size, however after growfs has run the
image may no longer boot.

Reviewed by: gjb, emaste, imp
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D14343