add some more necessary device entries
introduce makedisk_minimal() and use it to create the CD-ROM & md entries;
this procedure only creates 'a' and RAW_PART device entries
remove pf from 'all' target - it's not part of tree, so shouldn't be
created by default
for tty0[0-9]
as pointed out by David Laight
remove spaces between makedisk_p*() functions, so the output script looks
neater once some of them are filtered out
