device: Add scan_generic_bus support

scan_smbus routine does not perform any smbus specific operation. Thus,
rename the routine to scan_generic_bus so that it can be used by other
buses like SPI. Add a wrapper scan_smbus to allow other users of smbus
scan to continue working as before.

BUG=chrome-os-partner:59832
BRANCH=None
TEST=Compiles successfully

Change-Id: I8ca1a2b7f2906d186ec39e9223ce18b8a1f27196
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/18363
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/src/include/device/device.h b/src/include/device/device.h
index e21384b..284c039 100644
--- a/src/include/device/device.h
+++ b/src/include/device/device.h
@@ -241,6 +241,7 @@
 void mmconf_resource(struct device *dev, unsigned long index);
 
 void scan_smbus(device_t bus);
+void scan_generic_bus(device_t bus);
 void scan_static_bus(device_t bus);
 void scan_lpc_bus(device_t bus);