The build-iso script was attempting to populate the "upgrades"
path of the ISO from an invalid source. This change uses the
correct source files for population of the path.
Change-Id: I28d0a762052b9dcaf0cad85d52207404e5919474
Closes-Bug: 1798890
Signed-off-by: Jason McKenna <jason.mckenna@windriver.com>