MIPS: Loongson64: DTS: Add RTC support to Loongson-2K1000

[ Upstream commit e47084e1

 ]

The module is now supported, enable it.

Acked-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Stable-dep-of: dbb69b9d6234 ("MIPS: dts: loongson: Fix liointc IRQ polarity")
Signed-off-by: Sasha Levin <sashal@kernel.org>