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: Bastian Krause <bst@pengutronix.de>
Link: https://lore.kernel.org/r/20190830134755.1121-1-bst@pengutronix.de


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>