[SCSI] scsi_transport_spi: fix oops in revalidate

The class_device->device conversion is causing an oops in revalidate
because it's assuming that the device_for_each_child iterator will only
return struct scsi_device children.  The conversion made all former
class_devices children of the device as well, so this assumption is
broken.  Fix it.

Cc: Stable Tree <stable@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/scsi_transport_spi.c

@@ -366,12 +366,14 @@ spi_transport_rd_attr(rti, "%d\n");
 spi_transport_rd_attr(pcomp_en, "%d\n");
 spi_transport_rd_attr(hold_mcs, "%d\n");
 
-/* we only care about the first child device so we return 1 */
+/* we only care about the first child device that's a real SCSI device
+ * so we return 1 to terminate the iteration when we find it */
 static int child_iter(struct device *dev, void *data)
 {
-	struct scsi_device *sdev = to_scsi_device(dev);
+	if (!scsi_is_sdev_device(dev))
+		return 0;
 
-	spi_dv_device(sdev);
+	spi_dv_device(to_scsi_device(dev));
 	return 1;
 }