some submits to crochet for Orange Pi - PC Plus and One

[Curtis Villamizar]

FYI-

I just did four crochet pull requests.  Due to pilot error they are
cummulative so taking the last takes all the changes.  Oops.

The changes (at https://github.com/freebsd/crochet/pulls) are:

  Change the default IMAGE_SIZE for RaspberryPi2 board

  increase IMAGE_SIZE for RaspberryPi3 to 3GB - no longer fits in 2GB

  Add OrangePi-PC-Plus board directory

  Add OrangePi-One board directory

That should be self explanitory.  I have built and have running the
RaspberryPi3, OrangePi-PC-Plus, and OrangePi-One.  The RPi2 was
stillborn, likely due to building before
https://svnweb.freebsd.org/changeset/base/333177

Bottom line is OrangePi-PC-Plus and OrangePi-One now build using
crochet.  More info on building and additional progress (with ports)
is described at http://occnc.com/info/arm64/NOTES.html .

Related - also submitted fix/workaround to math/gmp port
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=228082

Curtis