Only add the first found widevine CDM

Otherwise Chromium will pick the last added, meaning we will use the
wrong one.

Task-number:  QTBUG-64071
Change-Id: Id5c939b6a5c70643ed047625c0cbb152dd8c7169
Reviewed-by: Alexandru Croitor <[email protected]>
(cherry picked from commit bd3687d)
Reviewed-by: Michael Brüning <[email protected]>

Author: Allan Sandfeld Jensen

src/core/content_client_qt.cpp

@@ -268,6 +268,7 @@ void AddPepperWidevine(std::vector<content::PepperPluginInfo>* plugins)
             widevine_cdm.mime_types.push_back(widevine_cdm_mime_type);
             widevine_cdm.permissions = kWidevineCdmPluginPermissions;
             plugins->push_back(widevine_cdm);
+            break;
         }
     }
 #endif  // defined(WIDEVINE_CDM_AVAILABLE) && BUILDFLAG(ENABLE_PEPPER_CDMS) &&