pcnet32: only allocate init_block dma consistent

The patch below moves the init_block out of the private struct and
only allocates init block with pci_alloc_consistent.

This has two effects:

1. Performance increase for non cache coherent machines, because the
   CPU only data in the private struct are now cached

2. locks are working now for platforms, which need to have locks
   in cached memory

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: Don Fry <pcnet32@verizon.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>