avr32: Fix MIMC200 board use of SPD network pins

The MIMC200 board uses the SPD output pin from the Ethernet MACs for
other purposes.

One of these is as a board-reset, so I've had to #define off the SPD
output pin declaration.

This is probably not the best way of achieving this, but works in the
current framework.

Signed-off-by: Mark Jackson <mpfj@mimc.co.uk>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>