xenial-amd64-tf-m-build: add device-tree-compiler package

dtc is required for TF-A CI scripts. In addition, sort the packages
list.

Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>
Change-Id: I4ea5cf8ac4c16e3f5f9ebd9afd91a8772cc4bc23
1 file changed