tf-a-main: add linux boot tests for QEMU

Add basic linux boot tests for QEMU to the main job. We currently only
test against FVPs and Juno, add this as an extra sanity check.

Change-Id: I46ac64a0653e2bca56bbad665e13b515a04ee61c
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
1 file changed