As we convert sockaddr for AF_PACKET family for sendto() (target to
host) we need also to convert this for getsockname() (host to target).

arping uses getsockname() to get the the interface address and uses
this address with sendto().

Tested with:

    /sbin/arping -D -q -c2 -I eno1 192.168.122.88

...
getsockname(3, {sa_family=AF_PACKET, proto=0x806, if2,
pkttype=PACKET_HOST, addr(6)={1, 10c37b6b9a76}, [18]) = 0
...
sendto(3, "..." 28, 0,
       {sa_family=AF_PACKET, proto=0x806, if2, pkttype=PACKET_HOST,
       addr(6)={1, ffffffffffff}, 20) = 28
...
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>