[PATCH] pata_amd: Check enable bits on Nvidia

A couple of people reported long delays on probe with the newer kernels
and Nvidia PATA. This turned out to be because the Nvidia path forgot to
check the enable bits so probed empty ports.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>