Fix device discovery in NitrokeyManager::connect_with_path

The device discovery in NitrokeyManager's connect_with_path method is
broken. It tries to statically determine the vendor ID by using the
first working HID pointer. That's obviously not working when a both a
Nitrokey device and Librem Key are connected and the path is describing
a Librem Key. In such a case the vendor ID used would be that for the
Nitrokey and we would not be able to find the Librem Key at all. This
change fixes up the logic.

NitrokeyManager.cc

@@ -217,44 +217,44 @@ using nitrokey::misc::strcpyT;
             }
         }
 
-	auto vendor_id = NITROKEY_VID;
-        auto info_ptr = hid_enumerate(vendor_id, 0);
-	if (!info_ptr) {
-	  vendor_id = PURISM_VID;
-	  info_ptr = hid_enumerate(vendor_id, 0);
-	}
-        auto first_info_ptr = info_ptr;
-        if (!info_ptr)
-          return false;
+        auto vendor_ids = { NITROKEY_VID, PURISM_VID };
+        for (auto vendor_id : vendor_ids) {
+          auto info_ptr = hid_enumerate(vendor_id, 0);
+          if (!info_ptr) {
+            continue;
+          }
+          auto first_info_ptr = info_ptr;
+
+          misc::Option<DeviceModel> model;
+          while (info_ptr && !model.has_value()) {
+              if (path == std::string(info_ptr->path)) {
+                  model = product_id_to_model(info_ptr->vendor_id, info_ptr->product_id);
+              }
+              info_ptr = info_ptr->next;
+          }
+          hid_free_enumeration(first_info_ptr);
 
-        misc::Option<DeviceModel> model;
-        while (info_ptr && !model.has_value()) {
-            if (path == std::string(info_ptr->path)) {
-                model = product_id_to_model(info_ptr->vendor_id, info_ptr->product_id);
-            }
-            info_ptr = info_ptr->next;
-        }
-        hid_free_enumeration(first_info_ptr);
+          if (!model.has_value())
+            continue;
 
-        if (!model.has_value())
+          auto p = Device::create(model.value());
+          if (!p)
             return false;
+          p->set_path(path);
 
-        auto p = Device::create(model.value());
-        if (!p)
-            return false;
-        p->set_path(path);
+          if(!p->connect()) return false;
 
-        if(!p->connect()) return false;
+          if(cache_connections){
+              connected_devices [path] = p;
+          }
 
-        if(cache_connections){
-            connected_devices [path] = p;
+          device = p; //previous device will be disconnected automatically
+          current_device_id = path;
+          nitrokey::log::Log::setPrefix(path);
+          LOGD1("Device successfully changed");
+          return true;
         }
-
-        device = p; //previous device will be disconnected automatically
-        current_device_id = path;
-        nitrokey::log::Log::setPrefix(path);
-        LOGD1("Device successfully changed");
-        return true;
+        return false;
     }
 
     bool NitrokeyManager::connect() {