ipnetconf: by default dump all entries

ipnetconf: by default dump all entries

This is now possible, because the dump function has been added in kernel.
Note that IPv4 and IPv6 entries are displayed.

Before this patch, only all entries were displayed.

Example:
$ ip netconf
ipv4 dev lo forwarding on rp_filter off mc_forwarding 0
ipv4 dev eth0 forwarding on rp_filter off mc_forwarding 1
ipv4 all forwarding on rp_filter off mc_forwarding 1
ipv4 default forwarding on rp_filter off mc_forwarding 0
ipv6 dev lo forwarding on mc_forwarding 0
ipv6 dev eth0 forwarding on mc_forwarding 0
ipv6 all forwarding on mc_forwarding 0
ipv6 default forwarding on mc_forwarding 0

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>