mm-base-manager: remove element from hastable by key, not value

The hashtable is keyed on the UID of the MMDevice, and its hash
function is g_str_hash. We shouldn't be passing a GObject into
g_hash_table_remove because calling g_str_hash on an MMDevice is
wrong.

src/mm-base-manager.c

@@ -628,7 +628,7 @@ remove_disable_ready (MMBaseModem *modem,
     if (device) {
         g_cancellable_cancel (mm_base_modem_peek_cancellable (modem));
         mm_device_remove_modem (device);
-        g_hash_table_remove (self->priv->devices, device);
+        g_hash_table_remove (self->priv->devices, mm_device_get_uid (device));
     }
 }