arm64: dts: rockchip: Add spi nodes on rk356x

This adds the four spi nodes (spi0, spi1, spi2, spi3) to the
rk356x dtsi. These are from the downstream device tree, though
I have double-checked that their interrupts and DMA numbers are
correct. I have also tested spi1 with an SPI device.

Signed-off-by: Nicolas Frattaroli <frattaroli.nicolas@gmail.com>
Link: https://lore.kernel.org/r/20211127141910.12649-3-frattaroli.nicolas@gmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>