Initial changes for upcoming MVME1[67]7 support.
Make this compile again.
Fix TBIA usage for non-68030 case.
Make the ethernet packet buffer shared between the Lance and i82596
drivers.

While I'm here, make the packet buffer size adjustable, either with
a config file option or by patching a variable. Make sure to mark all
packet buffer pages as non-cacheable.
Add mvme68k/machdep.h and start populating with external
declarations for a couple of mvme68k globals.
Include the above file where necessary.
The further adventures of mvme167 support. Mostly working now.
Fix typo.
m68k/m68k/cacheops.c needed for building mixed 030/040 kernels.
Make this assemble for mixed '147/'167 support.