MILO and 21064A D-cache size

[Nikita Schmidt <cetus@snowball.ucd.ie>]

I have put new MILOs for 21064[A]-based platforms (Avanti, Cabriolet,
EB64+, Mikasa), which enable 16 kB D-cache on 21064A.  The older MILOs
treated 21064A as 21064 and initialised it in 8 kB D-cache mode.

The only difference between -c5.4 and -c5.5 is the PALcode patch for
21064, so I did not re-build 21066 and 21164 MILOs.

Nikita