ARM: dts: kirkwood: synology: Fix rs5c372 RTC entry

In the rtc-rs5c372.c driver the compatible entry has been renamed
from rs5c372 to rs5c372a. Most dts files have been adapted.
This patch completes the change.
Signed-off-by: Walter Schweizer <ws.kernel@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>

arch/arm/boot/dts/kirkwood-synology.dtsi

@@ -244,7 +244,7 @@ i2c@11000 {
 
 			rs5c372: rs5c372@32 {
 				status = "disabled";
-				compatible = "ricoh,rs5c372";
+				compatible = "ricoh,rs5c372a";
 				reg = <0x32>;
 			};