bareudp: Fixed bareudp receive handling

Reverted commit "2baecda3 bareudp: remove unnecessary udp_encap_enable() in
bareudp_socket_create()"

An explicit call to udp_encap_enable is needed as the setup_udp_tunnel_sock
does not call udp_encap_enable if the if the socket is of type v6.

Bareudp device uses v6 socket to receive v4 & v6 traffic

CC: Taehee Yoo <ap420073@gmail.com>
Fixes: 2baecda3

 ("bareudp: remove unnecessary udp_encap_enable() in bareudp_socket_create()")
Signed-off-by: Martin Varghese <martin.varghese@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>