ARM: dts: AM4372: Add the am4372-rtc compatible string

am4372-rtc string was already part of dts, introduced to identify
the rtc specific to am4372 family of SoCs. It was removed in one of the
previous patches. Adding back the same with appropriate documentation.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
diff --git a/arch/arm/boot/dts/am4372.dtsi b/arch/arm/boot/dts/am4372.dtsi
index 15fbc56..6bc8b49 100644
--- a/arch/arm/boot/dts/am4372.dtsi
+++ b/arch/arm/boot/dts/am4372.dtsi
@@ -330,7 +330,8 @@
 		};
 
 		rtc: rtc@44e3e000 {
-			compatible = "ti,am3352-rtc", "ti,da830-rtc";
+			compatible = "ti,am4372-rtc", "ti,am3352-rtc",
+				     "ti,da830-rtc";
 			reg = <0x44e3e000 0x1000>;
 			interrupts = <GIC_SPI 75 IRQ_TYPE_LEVEL_HIGH
 				      GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>;