tdf#118948 - Date format in Impress header/footer is lost when saving

regression from
    commit 7d14555e
    convert SvxDateFormat to scoped enum

Change-Id: I9d365c710a20054e249433f54635068f713afa72
Reviewed-on: https://gerrit.libreoffice.org/58202
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

sd/source/ui/unoidl/unopage.cxx

@@ -1262,7 +1262,7 @@ Any SAL_CALL SdGenericDrawPage::getPropertyValue( const OUString& PropertyName )
     case WID_PAGE_DATETIMEFORMAT:
         {
             auto const & rSettings = GetPage()->getHeaderFooterSettings();
-            sal_Int32 x = static_cast<sal_Int32>(rSettings.meDateFormat) & (static_cast<sal_Int32>(rSettings.meTimeFormat) << 4);
+            sal_Int32 x = static_cast<sal_Int32>(rSettings.meDateFormat) | (static_cast<sal_Int32>(rSettings.meTimeFormat) << 4);
             aAny <<= x;
         }
         break;