dt-bindings: rtc: add Epson RX-8025 and RX-8035

These are supported by the rtc-rx8025 module. RX-8025
also has support in ds1307 due to compatible time registers.

Signed-off-by: Mathew McBride <matt@traverse.com.au>
Reviewed-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210709044518.28769-3-matt@traverse.com.au