[CMLIB] Simplify an ASSERTMSG() as an ASSERT().

sdk/lib/cmlib/cmindex.c

@@ -1285,7 +1285,7 @@ CmpSelectLeaf(IN PHHIVE Hive,
     if (!IndexKey)
     {
         /* Should not happen! */
-        ASSERTMSG("IndexKey = NULL!, it should not happen!\n", FALSE);
+        ASSERT(IndexKey != NULL);
         return HCELL_NIL;
     }