net/utils: Introduce inet_addr_is_any

Can be useful to check INET_ANY address for both ipv4/ipv6 addresses.

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>