dt-bindings: rtc: ds1307: add rx8130 compatible

The required OF entries were added with commit 47dd4729
("rtc: ds1307: add OF and ACPI entries for Epson RX8130").

Cc: devicetree@vger.kernel.org
Signed-off-by: NBastian Krause <bst@pengutronix.de>
Link: https://lore.kernel.org/r/20190830134755.1121-1-bst@pengutronix.deSigned-off-by: NAlexandre Belloni <alexandre.belloni@bootlin.com>

Documentation/devicetree/bindings/rtc/rtc-ds1307.txt

@@ -19,6 +19,7 @@ Required properties:
 	"pericom,pt7c4338",
 	"epson,rx8025",
 	"isil,isl12057"
+	"epson,rx8130"
 - reg: I2C bus address of the device
 
 Optional properties: