parameters: Fix handling of non-list extra_hosts sequence
parameters: Fix handling of non-list extra_hosts sequence

Signed-off-by: Esben Haabendal <da90c138e4a9573086862393cde34fa33d74f6e5@haabendal.dk>

esben/xd-docker,esben/xd-docker,XD-embedded/xd-docker,XD-embedded/xd-docker