ARM: tegra: pull Tegra20 SoC DT from Linux v4.7

This brings in a few minor fixes since the last sync. The largest change
is the removal of the definition for TEGRA20_CLK_PCIE_XCLK. This clock
doesn't actually exist.

Remaining deltas:
* Addition of u-boot,dm-pre-reloc property to a couple of nodes.
* Addition of the NAND controller, which Linux doesn't yet support.

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