ARM: tegra: Add p2371-2180 board

P2371-2180 is a P2180 CPU board married to a P2597 I/O board. The
combination contains SoC, DRAM, eMMC, SD card slot, HDMI, USB
micro-B port, Ethernet via USB3, USB3 host port, SATA, PCIe, and
two GPIO expansion headers.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>