gsm_04_11_gsup.c: drop unused conn lookup

An earlier code state used the conn to lookup the transaction, but this is now
done by vsub. Hence the conn lookup is not used and not needed.

conn is no longer used since 36c44b210059bd75059008913ad05976dfef7d7e,
change-Id I093f36d63e671e50e54fc6236e97a777cc6da77b,
"transaction: change arguments of trans_find_by_sm_rp_mr()"

Change-Id: Ia878d70138c883cb1a1d983516aff83efa6488ce
1 file changed