powerpc: gamecube/wii: do not include PCI support

The Nintendo GameCube and Wii video game consoles do not have PCI hardware.
Avoid wasting their scarce memory by not including PCI support into the
kernel.

Signed-off-by: Albert Herranz <albert_herranz@yahoo.es>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>