devicetree: Discriminate device ops scan_bus()

Use of scan_static_bus() and tree traversals is somewhat convoluted.
Start cleaning this up by assigning each path type with separate
static scan_bus() function.

For ME, SMBus and LPC paths a bus cannot expose bridges, as those would
add to the number of encountered PCI buses.

Change-Id: I8bb11450516faad4fa33b8f69bce5b9978ec75e5
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/8534
Tested-by: build bot (Jenkins)
Reviewed-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
diff --git a/src/southbridge/intel/ibexpeak/smbus.c b/src/southbridge/intel/ibexpeak/smbus.c
index 085aec0..2bb4cbf 100644
--- a/src/southbridge/intel/ibexpeak/smbus.c
+++ b/src/southbridge/intel/ibexpeak/smbus.c
@@ -108,7 +108,7 @@
 	.read_resources		= smbus_read_resources,
 	.set_resources		= pci_dev_set_resources,
 	.enable_resources	= pci_dev_enable_resources,
-	.scan_bus		= scan_static_bus,
+	.scan_bus		= scan_smbus,
 	.init			= pch_smbus_init,
 	.ops_smbus_bus		= &lops_smbus_bus,
 	.ops_pci		= &smbus_pci_ops,