ARM: tegra: set up /aliases entries for RTCs

This ensures that the PMIC RTC provides the system time, rather than
the on-SoC RTC, which is not battery-backed.

tegra124-venice2.dts isn't touched yet since we haven't added any off-
SoC RTC device to its device tree.

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 1204738..a11b6e7 100644
--- a/arch/arm/boot/dts/tegra20-seaboard.dts
+++ b/arch/arm/boot/dts/tegra20-seaboard.dts
@@ -7,6 +7,11 @@
 	model = "NVIDIA Seaboard";
 	compatible = "nvidia,seaboard", "nvidia,tegra20";
 
+	aliases {
+		rtc0 = "/i2c@7000d000/tps6586x@34";
+		rtc1 = "/rtc@7000e000";
+	};
+
 	memory {
 		reg = <0x00000000 0x40000000>;
 	};