breakpoint address before it's used. Currently a no-op on all but sh5.
This is useful on sh5, for example, to mask off the instruction
type encoding in the bottom two address bits, and makes it possible
to do "db> break $rXX" instead of manually munging the address.
add bus_dma support for the vs4000 dma translation map (sgmap).
enhance the vsbus for the lance to work with it.
remove the sgmap init code from ka46/48/49.c
