Fix the function invocation which missed the package name.

The issue was introduced in the last refactoring, but the logic using the function is currently not used so nothing is broken.

Bug: 303904827
Test: CIs
Change-Id: I428e5b8d525ec49d0d5f62b7fbcc54caf482ac59
diff --git a/tools/sbom/generate-sbom.py b/tools/sbom/generate-sbom.py
index 5eae262..72f896b 100755
--- a/tools/sbom/generate-sbom.py
+++ b/tools/sbom/generate-sbom.py
@@ -347,7 +347,7 @@
       sbom_checksum = metadata_proto.third_party.sbom_ref.checksum
       upstream_element_id = metadata_proto.third_party.sbom_ref.element_id
       if sbom_url and sbom_checksum and upstream_element_id:
-        doc_ref_id = f'DocumentRef-{PKG_UPSTREAM}-{encode_for_spdxid(name)}'
+        doc_ref_id = f'DocumentRef-{PKG_UPSTREAM}-{sbom_data.encode_for_spdxid(name)}'
         external_doc_ref = sbom_data.DocumentExternalReference(id=doc_ref_id,
                                                                uri=sbom_url,
                                                                checksum=sbom_checksum)