networking: code shrink

networking: code shrink

function                                             old     new   delta
in_ether                                               -     124    +124
hexchar2int                                           42       -     -42
ifconfig_main                                       1237    1106    -131
ether_input                                          141       -    -141
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 0/1 up/down: 124/-314)         Total: -190 bytes

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>