ARM: dt: tegra: configure power off for some boards

For Seaboard, Ventana, and Cardhu, add DT property to tell the regulator
that it should provide the pm_power_off() implementation. This allows
"shutdown" to work.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
diff --git a/arch/arm/boot/dts/tegra20-seaboard.dts b/arch/arm/boot/dts/tegra20-seaboard.dts
index 92deb36..e60dc71 100644
--- a/arch/arm/boot/dts/tegra20-seaboard.dts
+++ b/arch/arm/boot/dts/tegra20-seaboard.dts
@@ -379,6 +379,8 @@
 			reg = <0x34>;
 			interrupts = <0 86 0x4>;
 
+			ti,system-power-controller;
+
 			#gpio-cells = <2>;
 			gpio-controller;