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/i82371eb/isa.c b/src/southbridge/intel/i82371eb/isa.c
index 1945fae..024604b 100644
--- a/src/southbridge/intel/i82371eb/isa.c
+++ b/src/southbridge/intel/i82371eb/isa.c
@@ -145,7 +145,7 @@
 	.acpi_fill_ssdt_generator = southbridge_acpi_fill_ssdt_generator,
 #endif
 	.init			= isa_init,
-	.scan_bus		= scan_static_bus,	/* TODO: Needed? */
+	.scan_bus		= scan_lpc_bus,	/* TODO: Needed? */
 	.enable			= 0,
 	.ops_pci		= 0, /* No subsystem IDs on 82371EB! */
 };