ARM: tegra: dts: Add pwm label

PWM devices can be referenced in the DT by phandle and per-chip index.
In order for this to work properly, the PWM controller needs to have a
label attached to it.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
diff --git a/arch/arm/boot/dts/tegra20.dtsi b/arch/arm/boot/dts/tegra20.dtsi
index 405d167..67a6cd9 100644
--- a/arch/arm/boot/dts/tegra20.dtsi
+++ b/arch/arm/boot/dts/tegra20.dtsi
@@ -123,7 +123,7 @@
 		status = "disabled";
 	};
 
-	pwm {
+	pwm: pwm {
 		compatible = "nvidia,tegra20-pwm";
 		reg = <0x7000a000 0x100>;
 		#pwm-cells = <2>;