icache, dcache: fix invalidate on first write for 1-way cache
cappuccino/fetch: hold the bus line for ic during refill
icache: only ack during refill when ic_access_i is asserted

the icache ack line might still be muxed onto the outgoing
ack while waiting out a refill, we can't ack on those requests
cappuccino/lsu: hold the bus line for dc during refill