Use correct pointer in key_updateaddresses() when updating NAT-T config.

key_updateaddresses() is used to update SA addresses and NAT-T
configuration in SADB_UPDATE message. This is done using cloning SA
content from old SA into new one. But addresses and NAT-T configuration
are taking from SADB_UPDATE message. Use newsa pointer to set NAT-T
properties into cloned SA.

PR:		[[ https://bugs.freebsd.org/223382 | 223382 ]]