commit f3a2ddc124 ("lib utils: Use helpers to get AF bit/byte len")
used a wrong family or family of zero in the default case
during af_bit_len calculation causing ip route commands to
fail with below error
Error: an inet prefix is expected rather than "10.0.2.14/24".
Reported-by: Sven-Haegar Koch <haegar@sdinet.de>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>