powerpc/ci: Fix boot issues with corenet32_smp_defconfig for e500mc

We only have fedora image specified for kernel build for
corenet32_smp_defconfig. So remove the old-image korg-8.1.0 from
the boot matrix.

Also add conditional checks to see if old-image is actually available
for doing download artifact & boot steps.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
1 file changed