A variant of the M.2 RAID enablement kit does not manifest with nvme
driver. Address this by allowing 'nvm' subsystype. to allow blank driver.
Also, to be on the safe side, have self.driver always be a string,
so it can be 'falsey' but still work as a string.
If syncfiles fails, keep it retrying.
Also, slow down sync checking to avoid hammering the system.
Further, randomized delay to spread highly synchronized requestors.
Block attempts to do multiple concurrent syncfile runs.
Some versions start manifesting nvme devnames with 'c', which
are to be used to interact with multipath to have raw devices
backing a traditional nvme device.
Needed the real losetup to handle read-only file.
busybox wc is way too slow, use ls instead.
Explicitly make /sysroot and load xfs, as that doesn't happen implicitly.
Accept a dangling symlink as viable init, since this is the case in Ubuntu.
Update hostname and ca certificates consistent with
ubuntu standards
