fib: fix another fib_rules_ops indirect call wrapper problem

It turns out that on commit 41d707b7 ("fib: fix fib_rules_ops
indirect calls wrappers") I forgot to include the case when
CONFIG_IP_MULTIPLE_TABLES is not set.

Fixes: 41d707b7 ("fib: fix fib_rules_ops indirect calls wrappers")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Brian Vazquez <brianvv@google.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: David S. Miller <davem@davemloft.net>