packer_freebsd.json: using "su root -c" instead of "sudo"

We don't have "sudo" pre-installed in the image.
So, using "su root -c" instead of "sudo" to run the script.

Signed-off-by: Arthur She <arthur.she@linaro.org>
Change-Id: If77d290399fca882a54e0b4e11137b04489fb775
1 file changed
tree: 2d1137656296b81f6469b541b745812628fb678a
  1. freebsd.sh
  2. packer_freebsd.json
  3. packer_ubuntu.json
  4. ubuntu.sh