udhcpd: code shrink

udhcpd: code shrink

function                                             old     new   delta
send_packet_verbose                                    -      35     +35
send_offer                                           443     423     -20
send_ACK                                             152     131     -21
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/2 up/down: 35/-41)             Total: -6 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>