according to “TX2 serious pinmux”, GEN1_I2C_SCL maps to GPIO3_PC.05, GEN1_I2C_SDA maps to GPIO3_PC.06.
reference to topic,
cat /sys/kernel/debug/gpio | grep -C 5 342
gpio-337 ( )
gpio-338 ( )
gpio-339 ( )
gpio-340 ( )
gpio-341 ( )
gpio-342 ( )
gpio-343 ( )
gpio-345 ( )
gpio-346 ( )