producer: remove unused db operation

Change-Id: Ibce86e9c74ba05f0b1c8c3106f79a94660f3559b
Refs: #3354
diff --git a/src/producer.cpp b/src/producer.cpp
index f112fa6..81c1349 100644
--- a/src/producer.cpp
+++ b/src/producer.cpp
@@ -84,7 +84,6 @@
 
   Buffer contentKeyBits;
   if (m_db.hasContentKey(timeslot)) {
-    contentKeyBits = m_db.getContentKey(timeslot);
     return contentKeyName;
   }
 
@@ -238,4 +237,4 @@
 }
 
 } // namespace gep
-} // namespace ndn
\ No newline at end of file
+} // namespace ndn