ARA-M: fix encoding of the PkgRefDO when using aram_store_ref_ar_do

The command wasn't used the correct dict to allow the encoders to work.

Related: OS#6121
Change-Id: Ic2bc179b413a6b139e07e3e55b93ff921cb020a9
diff --git a/pySim/ara_m.py b/pySim/ara_m.py
index e2e6da1..8144381 100644
--- a/pySim/ara_m.py
+++ b/pySim/ara_m.py
@@ -354,7 +354,7 @@
                 ref_do_content += [{'aid_ref_empty_do': None}]
             ref_do_content += [{'dev_app_id_ref_do': opts.device_app_id}]
             if opts.pkg_ref:
-                ref_do_content += [{'pkg_ref_do': opts.pkg_ref}]
+                ref_do_content += [{'pkg_ref_do': {'package_name_string': opts.pkg_ref}}]
             # AR
             ar_do_content = []
             if opts.apdu_never: