[IPV4] fib_trie: missing ntohl() when calling fib_semantic_match()

fib_trie.c::check_leaf() passes host-endian where fib_semantic_match()
expects (and stores into) net-endian.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>