driver. This is taken from the MAC at boot, but can be overridden with
'options AT91_MACB_USE_RMII'.
Switch to macb for HL201 and SAM9G20EK boards. It now works both
places. Also start to sneak up on FDT for the SAM9G20EK board, but
leave disabled due to issues with MMC that haven't been resolved.
Add early debug support for the SAM9G20EK since that is required
for FDT to work presently on these SoC.