dev board: RN1 should be 4 discrete 0805 resistors

[jonas-schievink]

Currently RN1 is a 4x0603 10k resistor array, which is apparently not easy to get (I substituted discrete 0603 resistors because Digikey didn't have a fitting resistor array). It should be replaced by 4 discrete 10k 0805 resistors, which would mean that the board has a total of 10 of these resistors, which can lower cost a little bit.