Follow-up to 09794ef832 -
initfs file does not have flavor now, too.
Without this 'pmbootstrap initfs extract' fails with:
(rootfs_samsung-klte) % cp /boot/initramfs-postmarketos-qcom-msm8974 /tmp/initfs-extracted/_initfs.gz
cp: cannot stat '/boot/initramfs-postmarketos-qcom-msm8974': No such file or directory