ARM: dts: omap3-tobi: Use the correct vendor prefix

Gumstix is the correct vendor for all Overo related products.
Reported-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Florian Vaussard <florian.vaussard@epfl.ch>
Acked-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/omap3-tobi.dts

@@ -17,7 +17,7 @@
 
 / {
 	model = "TI OMAP3 Gumstix Overo on Tobi";
-	compatible = "ti,omap3-tobi", "ti,omap3-overo", "ti,omap36xx", "ti,omap3";
+	compatible = "gumstix,omap3-tobi", "gumstix,omap3-overo", "ti,omap36xx", "ti,omap3";
 
 	leds {
 		compatible = "gpio-leds";