ARM: dts: Add DTS for Gumstix TobiDuo expansion board

The Gumstix "Tobi-Duo" expansion board [1] can be used with either
OMAP3 Overo or Overo Storm COMs.  It provides two NICs using LAN9221
chips.
It is necessary to duplicate the interface information for the
second SMSC9221 chip as discussed [2].

[1] https://store.gumstix.com/index.php/products/241/
[2] http://www.spinics.net/lists/linux-omap/msg115282.html



Signed-off-by: Ash Charles <ashcharles@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>