qemu-build: Simplify

This reverts some of the changes to the script made to support features
other than what it was meant to do: build a docker image, and build qemu
in that image.

In it's current form it's failing to produce a qemu artifact for the CI
system to use. By simplifying it we have a better chance of debugging
the issue, and in fact the issue has gone away.

Change-Id: Ia757c1139e964b240ea4a54ecc7e24a5894e4cd9
Signed-off-by: Joel Stanley <joel@jms.id.au>
1 file changed