core: find the existing modem for a port in the manager

src/mm-plugin.h

@@ -71,6 +71,7 @@ struct _MMPlugin {
                                               const char *subsys,
                                               const char *name,
                                               const char *physdev_path,
+                                              MMModem *existing,
                                               MMSupportsPortResultFunc callback,
                                               gpointer user_data);
 
@@ -95,6 +96,7 @@ struct _MMPlugin {
     MMModem * (*grab_port)    (MMPlugin *self,
                                const char *subsys,
                                const char *name,
+                               MMModem *existing,
                                GError **error);
 };
 
@@ -106,6 +108,7 @@ MMPluginSupportsResult mm_plugin_supports_port  (MMPlugin *plugin,
                                                  const char *subsys,
                                                  const char *name,
                                                  const char *physdev_path,
+                                                 MMModem *existing,
                                                  MMSupportsPortResultFunc callback,
                                                  gpointer user_data);
 
@@ -116,6 +119,7 @@ void mm_plugin_cancel_supports_port (MMPlugin *plugin,
 MMModem *mm_plugin_grab_port     (MMPlugin *plugin,
                                   const char *subsys,
                                   const char *name,
+                                  MMModem *existing,
                                   GError **error);
 
 #endif /* MM_PLUGIN_H */