Revert "fib_rules: fix error in backport of e9919a24d302 ("fib_rules: return 0...")"

This reverts commit d5c71a7c533e88a9fcc74fe1b5c25743868fa300 as the
patch that this "fixes" is about to be reverted...

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index c03dd21..bb26457 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -430,7 +430,6 @@
 		goto errout_free;
 
 	if (rule_exists(ops, frh, tb, rule)) {
-		err = 0;
 		if (nlh->nlmsg_flags & NLM_F_EXCL)
 			err = -EEXIST;
 		goto errout_free;