Fix up find_pci_device so that it can be used for scanning for devices

*other* than the main boot device.

src/core/main.c

@@ -176,7 +176,7 @@ int main ( void ) {
 	 *
 	 */
 	for ( ; ; disable ( &dev ), call_reset_fns() ) {
-	
+
 		/* Get next boot device */
 		if ( ! probe ( &dev ) ) {
 			/* Reached end of device list */
@@ -210,6 +210,24 @@ void exit(int status)
 }
 
 
+/*
+ * Set PCI device to use.
+ *
+ * This routine can be called by e.g. the ROM prefix to specify that
+ * the first device to be tried should be the device on which the ROM
+ * was physically located.
+ *
+ * Note that this is deliberately in main.c rather than pci.c, because
+ * this function should generalise to other bus types (e.g. ISAPnP),
+ * and we don't want to end up dragging in pci.o unnecessarily.
+ */
+void set_pci_device ( uint16_t busdevfn ) {
+	dev.devid.bus_type = PCI_BUS_TYPE;
+	dev.pci.busdevfn = busdevfn;
+	dev.pci.already_tried = 0;
+}
+
+
 #if 0
 
 static int main_loop(int state)