Don't skip STEP_IP when get_connectio() fails.

[David Cantrell <dcantrell redhat com>]

During an interactive install, STEP_IP would get skipped over
if the user had to go back and select a different interface.
Need to blank out ipv4method and ipv6method to take them to
the STEP_IP screen.

-- 
David Cantrell <dcantrell redhat com>
Red Hat / Honolulu, HI