change to PPMC DIO board pin numbering

An error was found in the driver for the PPMC boards that caused mis-numbering of the
hal pins. This only affects systems with more than one DIO board. The first board
has pins numbered dout.00.out through dout.07.out, which is correct. The second
board was numbered dout.09.out through dout.16.out, skipping over dout.08.out.

I have corrected the driver in the master and 2.5 branch of the source, so if you
build a system from the source or update when 2.5 comes out, you will have to
adjust your hal file to correct the numbering.

This only affects additional DIO boards, not the first one, and does not affect
Universal Stepper or Universal PWM Controller boards at all. (They use a
different enumeration procedure that didn't have this mistake in it.)

I just wanted to get this info out into the public so nobody gets a nasty
surprise!

Jon