arm64: dts: rockchip: Add DTS for FriendlyARM NanoPi R2S Plus

The R2S Plus is basically an R2S with additional eMMC.

The eMMC configuration for the DTS has been extracted and copied from
rk3328-nanopi-r2.dts, v2017.09 branch from the friendlyarm/uboot-rockchip
repository.

Signed-off-by: Sergey Bostandzhyan <jin@mediatomb.cc>
Link: https://lore.kernel.org/r/20240814170048.23816-2-jin@mediatomb.cc


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