arm:dts:santvend: Enable VEML7700 light sensor

An external VEML7700 sensor is connected to I2C3 bus on SantVend. Enable a corresponding driver, which will be bound to device on I2C3 bus at 0x10 address, in device tree. After that, the current reading of the sensor can be obtained via IIO sysfs interface (/sys/bus/iio/devices/iio:device0/in_illuminance_input).

root@192:~# cat /sys/bus/iio/devices/iio:device0/in_illuminance_input

14.002848

root@192:~# cat /sys/bus/iio/devices/iio:device0/in_illuminance_input

0.000000

root@192:~# cat /sys/bus/iio/devices/iio:device0/in_illuminance_input

2.007648

root@192:~# cat /sys/bus/iio/devices/iio:device0/in_illuminance_input

3110.008608