Merge pull request #6351 from aravindksg/fix_btl_ofi_valgrind

btl/ofi: Fix valgrind complaints on uninitialized pointer use

opal/mca/btl/ofi/btl_ofi_module.c

@@ -315,6 +315,7 @@ int mca_btl_ofi_finalize (mca_btl_base_module_t* btl)
 
     if (ofi_btl->rcache) {
         mca_rcache_base_module_destroy (ofi_btl->rcache);
+        ofi_btl->rcache = NULL;
     }
 
     free (btl);