MIPS: Loongson64: DTS: Fix PCIe port nodes for ls7a

[ Upstream commit d89a415ff8d5e0aad4963f2d8ebb0f9e8110b7fa ]

Add various required properties to silent warnings:

arch/mips/boot/dts/loongson/loongson64-2k1000.dtsi:116.16-297.5: Warning (interrupt_provider): /bus@10000000/pci@1a000000: '#interrupt-cells' found, but node is not an interrupt provider
arch/mips/boot/dts/loongson/loongson64_2core_2k1000.dtb: Warning (interrupt_map): Failed prerequisite 'interrupt_provider'

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
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>