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>

arch/arm/boot/dts/tegra20-trimslice.dts

@@ -7,6 +7,11 @@
 	model = "Compulab TrimSlice board";
 	compatible = "compulab,trimslice", "nvidia,tegra20";
 
+	aliases {
+		rtc0 = "/i2c@7000c500/rtc@56";
+		rtc1 = "/rtc@7000e000";
+	};
+
 	memory {
 		reg = <0x00000000 0x40000000>;
 	};