finish up the coding of the Intel Gb NIC... Many Many bugs to squash

finish up the coding of the Intel Gb NIC... Many Many bugs to squash

src/dev/i8254xGBe.cc:
src/dev/i8254xGBe.hh:
src/dev/i8254xGBe_defs.hh:
    finish coding the Intel Gb NIC device
src/dev/io_device.hh:
    we really don't want to be able to pass a null buffer to dma read, at least not the way we have things setup now... it won't work at all

--HG--
extra : convert_revision : 6739497232317ec407cfa7a96de4575a9a6cfc46