fvp|juno_utils.sh: several changes on yaml generation

This is a collection of changes required in order to produce correct
yaml files which ultimatelly are consumed by LAVA on behalf of
Open CI jobs [1]. Changes are done on top of [2], with the aim of
keeping [2] intact (the revert) and clearly identifying those required
changes while implementing & testing [1].

[1] https://review.trustedfirmware.org/c/ci/tf-a-job-configs/+/6217
[2] https://review.trustedfirmware.org/c/ci/tf-a-ci-scripts/+/6223

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: I8506416ef66ba283b336c82208ffc07bf0b2dc3b
diff --git a/script/gen_juno_linux_reboot_yaml.sh b/script/gen_juno_linux_reboot_yaml.sh
index 9690406..324f7f1 100755
--- a/script/gen_juno_linux_reboot_yaml.sh
+++ b/script/gen_juno_linux_reboot_yaml.sh
@@ -29,7 +29,7 @@
 
 bootloader_prompt="${bootloader_prompt:-juno#}"
 recovery_img_url="${recovery_img_url:-$(get_recovery_image_url)}"
-nfs_rootfs="${nfs_rootfs:-$juno_rootfs_url}"
+nfs_rootfs="${juno_rootfs_url:-$nfs_rootfs}"
 linux_prompt="${linux_prompt:-root@(.*):~#}"
 os="${os:-debian}"