MD MAKEDEV.conf. Not all ports have vcoda in their majors.foo files
and we shouldn't (re)assign major numbers on all ports before 5.0.
Should close PR port-sgimips/38962.
at MAXPARTITIONS/OLDMAXPARTITIONS in kernel sources, so that it wouldn't
need to be specified separately in MAKEDEV.conf
change platform MAKEDEV.conf to contain only MD targets and nothing else;
simplify the parsing in MAKEDEV.awk accordingly
this contains information about disk partitions used by platform,
and MD MAKEDEV targets, such as 'init', MD part of 'all',
as well as any other MD-specific targets not covered by MAKEDEV.tmpl
