Limit max of NUC472 EMAC recv frame len as 1518

Author: cyliangtw

features/netsocket/emac-drivers/TARGET_NUVOTON_EMAC/TARGET_NUC472/nuc472_eth.c

@@ -228,6 +228,9 @@ void numaker_eth_init(uint8_t *mac_addr)
     init_rx_desc();
 
     numaker_set_mac_addr(mac_addr);  // need to reconfigure hardware address 'cos we just RESET emc...
+
+    /* Limit the max receive frame length to 1514 + 4 */
+    EMAC->MRFL = 1518;
     reset_phy();
 
     EMAC->CTL |= EMAC_CTL_STRIPCRC_Msk | EMAC_CTL_RXON_Msk | EMAC_CTL_TXON_Msk | EMAC_CTL_RMIIEN_Msk | EMAC_CTL_RMIIRXCTL_Msk;