arm64: tegra: Add NVIDIA P2571 board support

The NVIDIA P2571 is an internal reference design that's very similar to
the P2371, but targetting different use-cases.
Signed-off-by: NThierry Reding <treding@nvidia.com>

arch/arm64/boot/dts/nvidia/Makefile

 dtb-$(CONFIG_ARCH_TEGRA_132_SOC) += tegra132-norrin.dtb
 dtb-$(CONFIG_ARCH_TEGRA_210_SOC) += tegra210-p2371-0000.dtb
+dtb-$(CONFIG_ARCH_TEGRA_210_SOC) += tegra210-p2571.dtb
 
 always		:= $(dtb-y)
 clean-files	:= *.dtb