ARM: dts: r9a06g032-rzn1d400-db: Enable rtc0

The RZ/N1D-DB board does have a battery to power the RTC. Enable the
RTC device on this board.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
Link: https://lore.kernel.org/r/20220608090850.92735-1-clement.leger@bootlin.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>