Decrease I2C timeout in config so it matches the previous 500 us timeout...

... as close as possible. This is necessary after fixing the NuttX I2C timeout logic. The fix was introduced here:
https://github.com/PX4/NuttX/commit/047ed5c93fc127163ec1fa2854f977962a94c2f5

And we have observed starvation of up to a second on some of the sensors.