This one in particular is ripe with opportunities to trigger a duplicate
node error in pfs_create_dir(), so we do actually want to error-check
it. The rest, more or less, should be expected not to fail. We'll
propagate the error from pfs_create_dir() back up and fail vfs
registration/module loading, which is decidedly a better failure mode
than a panic.
While we're here, convert two malloc() that weren't being error checked
to M_WAITOK -- we already wait in the rest of the function, might as
wel do the same here.
Add a missing newline to the pseudofs error mesage.