Reinstate the Mac hardware clock for CUDA ADB and Mac II ADB models.
It doesn't work properly on Mac IIsi ADB and PMU ADB yet, so leave them 
out.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>