Fix these build errors which occurred if there was no PHY:
chip/lpc17_40_ethernet.c:1643:31: error: expected expression before ';' token
ret lpc17_40_phyinit();
chip/lpc17_40_ethernet.c:3941:1: error: expected identifier or '(' before '{' token
{
chip/lpc17_40_ethernet.c:448:13: warning: 'lpc17_40_macmode' used but never defined
static void lpc17_40_macmode(uint8_t mode);