T210: Add support for 64-bit T210-based P2571 board

Based on Venice2, incorporates Stephen Warren's
latest P2571 pinmux table.

With Thierry Reding's 64-bit build fixes, this
will build and and boot in 64-bit on my P2571
(when used with a 32-bit AVP loader).

Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/configs/p2571_defconfig b/configs/p2571_defconfig
new file mode 100644
index 0000000..8494bb5
--- /dev/null
+++ b/configs/p2571_defconfig
@@ -0,0 +1,16 @@
+CONFIG_ARM=y
+CONFIG_TEGRA=y
+CONFIG_TEGRA210=y
+CONFIG_TARGET_P2571=y
+CONFIG_DEFAULT_DEVICE_TREE="tegra210-p2571"
+# CONFIG_CMD_IMI is not set
+# CONFIG_CMD_IMLS is not set
+# CONFIG_CMD_FLASH is not set
+# CONFIG_CMD_FPGA is not set
+# CONFIG_CMD_SETEXPR is not set
+# CONFIG_CMD_NFS is not set
+CONFIG_SPL_DM=y
+CONFIG_SPI_FLASH=y
+CONFIG_USB=y
+CONFIG_DM_USB=y
+CONFIG_USE_PRIVATE_LIBGCC=y