Add support for all devices to get requests from a timing memory bus.

Add support for all devices to get requests from a timing memory bus.
In the future, this can be used for actual data, but for now, it's
so that devices can respond to timing accesses properly.  This way,
an uncached access on a bus further away will take longer to respond.

dev/alpha_console.cc:
dev/alpha_console.hh:
    suport the separate IO bus

--HG--
extra : convert_revision : ececb70f5febfd00231f6e406f93b2a79be01261