nouveau: Set special lane map for the right chipset

The refactoring of the nv50 logic, introduced in 8663bc7c, modified the
test for the special lane map used on some Apple computers with Nvidia
chipsets. The tested MBA3,1 would still boot, but resume from suspend
stopped working. This patch restores the old test, which fixes the problem.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Acked-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>