core: allow plugins to stop probing and not support a modem

Previously plugins could only stop probing, *or* stop probing and
indicate support for a device.  For the Alcatel X200/X060s debacle
we need to stop probing and indicate that the plugin does not
support the device at all.

plugins/mm-plugin-huawei.c

@@ -79,7 +79,7 @@ getportmode_response_cb (MMPluginBaseSupportsTask *task,
                          GString *response,
                          GError *error,
                          guint32 tries,
-                         gboolean *out_fail,
+                         gboolean *out_stop,
                          guint32 *out_level,
                          gpointer user_data)
 {
@@ -116,7 +116,7 @@ curc_response_cb (MMPluginBaseSupportsTask *task,
                   GString *response,
                   GError *error,
                   guint32 tries,
-                  gboolean *out_fail,
+                  gboolean *out_stop,
                   guint32 *out_level,
                   gpointer user_data)
 {

plugins/mm-plugin-zte.c

@@ -66,7 +66,7 @@ custom_init_response_cb (MMPluginBaseSupportsTask *task,
                          GString *response,
                          GError *error,
                          guint32 tries,
-                         gboolean *out_fail,
+                         gboolean *out_stop,
                          guint32 *out_level,
                          gpointer user_data)
 {