qcacld-3.0: Fix -Wmissing-prototypes in csr_link_list

We want to enable the compiler's -Wmissing-prototypes switch, but
there is existing code that is generating warnings. Fix all warnings
in csr_link_list.

Change-Id: Iac3b07372d0bb3d949eb7f6dc3dd6b9c084619d2
CRs-Fixed: 1075575

core/sme/src/csr/csr_link_list.c

@@ -103,7 +103,7 @@ static inline void csr_list_insert_head(tListElem *pHead, tListElem *pEntry)
 }
 
 /* Insert pNewEntry before pEntry */
-void csr_list_insert_entry(tListElem *pEntry, tListElem *pNewEntry)
+static void csr_list_insert_entry(tListElem *pEntry, tListElem *pNewEntry)
 {
 	tListElem *pLast;
 	if (!pEntry) {