ARM: tegra: Add NVIDIA Jetson Nano Developer Kit support

The Jetson Nano Developer Kit is a Tegra X1-based development board. It
is similar to Jetson TX1 but it is not pin compatible. It features 4GB
of LPDDR4, a SPI NOR flash for early boot firmware and an SD card slot
used for storage.

HDMI 2.0 or DP 1.2 are available for display, four USB ports (3 USB 2.0
and 1 USB 3.0) can be used to attach a variety of peripherals and a PCI
Ethernet controller provides onboard network connectivity. NVMe support
has also been added. Env save is at the end of QSPI (4MB-8K).

A 40-pin header on the board can be used to extend the capabilities and
exposed interfaces of the Jetson Nano.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
Tested-by: Peter Robinson <pbrobinson@gmail.com>