totemknet: create_nozzle_device simplify check

ipaddr existence is checked for being not NULL by caller setup_nozzle.
Also ipaddr was passed to reparse_nozzle_ip_address function unchecked
so code would crash before reaching the actual check.

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Christine Caulfield <ccaulfie@redhat.com>