ramips: Update ARC Freestation profile

ramips: Update ARC Freestation profile

These devices are actually built around the 8devices Carambola dev board.

ARC FreeStation, Flex mARC, iFlex, and SplitStation devices are
supported with this image, see "ARCFlex Firmware Downloads":
http://www.antennas.com/wiki/index.php?title=ARC-OS_Firmware_Downloads_and_Revision_History

Funnily enough if present the external USB wlan ends up being wlan-0, with the
SoC device being wlan-1.

- Invert port map so special handling of vlan config can be removed.
- Add LED config similar to original ArcOS firmware.
- Add GPIO export for enabling PoE passthrough from ethernet port 0 to port 1
- Get MACs from factory partition.
- Update description to list supported devices.
- Carambola uses RT3050 (not RT3052), though my Carambola CPU
  actually reports itself as being an RT3350 while still having
  RT3050F markings.

Signed-off-by: Tobias Diedrich <ranma+openwrt@tdiedrich.de>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@36564 3c298f89-4303-0410-b956-a3cf2f4a3e73