make the cache access latency a parameter that is based on bus

make the cache access latency a parameter that is based on bus
ticks for the most commonly accessed devices.

dev/baddev.cc:
    Get rid of the constant cache access latency.
    For unimportant devices, don't add any latency.
dev/ide_ctrl.cc:
dev/ide_ctrl.hh:
dev/ns_gige.cc:
dev/pciconfigall.cc:
dev/pciconfigall.hh:
dev/tsunami_cchip.cc:
dev/tsunami_cchip.hh:
dev/tsunami_io.cc:
dev/tsunami_io.hh:
dev/tsunami_pchip.cc:
dev/tsunami_pchip.hh:
dev/uart.cc:
dev/uart.hh:
    make the cache access latency a parameter that is based on bus
    ticks.
dev/io_device.cc:
dev/io_device.hh:
    add an io latency variable
dev/ns_gige.hh:
    this moved to io_device.hh

--HG--
extra : convert_revision : 4883130feeaef48abee492eddf0b8eb40eb94789