The FRI2 has an optional serial expansion board. Enable the use of this
as a console for both syslinux and the OS.

Note: while the settings all appear to be correct, the serial port is
      not working on my test device in syslinux or the getty. The
      kernel messages do make their way to the serial port after PCI
      initialization.

Signed-off-by: Darren Hart <dvhart@linux.intel.com>