bus_space_handle_t now holds an address and two ASIs, one for normal accesses
and one for streaming accesses. This allows to map individual handles
different ways, so some can use MMU bypass accesses and others use virtual
addresses. bus_space_map() will now create handles that use bypass accesses
unles BUS_SPACE_MAP_LINEAR is passed in. So only pass in BUS_SPACE_MAP_LINEAR
if you absolutely *need* to use bus_space_vaddr(). This removes at least one
extra level of indirection and should reduce TLB misses.
32-bit kernels have problems accessing 64-bit addresses, so they always use
virtual addresses.
