ARM: dts: overo: Create a file for common Gumstix peripherals

Gumstix expansion boards share a couple of peripherals:
- uart3 is used for the console
- AT24C01 EEPROM on i2c3

Use this file for overo-tobi.

Signed-off-by: Florian Vaussard <florian.vaussard@epfl.ch>
Signed-off-by: Tony Lindgren <tony@atomide.com>