netfilter: Remove IP_CT_NEW_REPLY definition.

Remove the definition of IP_CT_NEW_REPLY from the kernel as it does
not make sense.  This allows the definition of IP_CT_NUMBER to be
simplified as well.

Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>