net/ipv4/ipconfig: really display the BOOTP/DHCP server's address.

Up to now, the debug and info messages from the ipconfig subsytem
claim to display the IP address of the DHCP/BOOTP server but
display instead the IP address of the bootserver.  Fix that.

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Signed-off-by: David S. Miller <davem@davemloft.net>