arm64: dts: ti: k3-am62a7-sk: Add alias for RTC

Adds alias for SoC RTC so that it gets assigned rtc0. PMIC node is
assigned rtc1 so that PMIC RTC gets probed as rtc1. This makes it
consistent for testing rtcwake with other AM62 devices where rtc0
is SoC RTC.

Signed-off-by: Vibhore Vardhan <vibhore@ti.com>
[k-willis@ti.com: Reworded commit message]
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Kendall Willis <k-willis@ti.com>
Link: https://lore.kernel.org/r/20250214232212.1158505-1-k-willis@ti.com


Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>