Move NFS and TFTP filesystems before the synthetic filesystems (bzip,
gzip, and split). "Real" filesystems should always be listed first so
that the "bare" filename is tried before alternate filenames. For PXE
booting in particular this can remove a lot of spurious pathname lookups.

While here, move splitfs to the bottom after the bzip and gzip filesystems
as it is the least often used.

Tested by: Prokash Sinha <psinha@panasas.com>
MFC after: 1 week