SPI support on 40 pin header - Jetson Nano devkit

For enabling SPI support for Jetson Nano please use this patch. This patch cover Jetson nano (eMMC and SDcard version) only.

SPI devices after applying the patch are available on /dev/spidev0.0 and /dev/spidev0.1 (as generic spidev devices). You can use spidev_test tool and shortcut MOSI/MISO pins to test if communication is working as expected.

Note: some extension boards with SPI chips maybe will not work due to the level shifters which are assembled on 40 pin header. Please refer to 40 pin header considerations for more details.