add all the registers we'll need to support for the Intel GbE device and support...

add all the registers we'll need to support for the Intel GbE device and support enough functionality make the driver think
the device is there, and in good working order.

src/dev/SConscript:
    add intel gbe to the dev SCons file
src/dev/i8254xGBe.cc:
src/dev/i8254xGBe.hh:
src/dev/i8254xGBe_defs.hh:
    use new manner of registers and implement all device registers that are touched through boot and ifup

--HG--
extra : convert_revision : b1a1767f0fd31cd371e432cb48ac9a2e9f9291b5