Adjust M460 EMAC RX/TX buffer

Author: cyliangtw

connectivity/drivers/emac/TARGET_NUVOTON_EMAC/TARGET_M460/synopGMAC_Dev.h

@@ -55,8 +55,8 @@ enum GMACPhyBase {
 #define DMABASE 0x1000          // Dma base address starts with an offset 0x1000
 
 
-#define TRANSMIT_DESC_SIZE  4//32//256 //Tx Descriptors needed in the Descriptor pool/queue
-#define RECEIVE_DESC_SIZE   4//32//256 //Rx Descriptors needed in the Descriptor pool/queue
+#define TRANSMIT_DESC_SIZE  8//256 //Tx Descriptors needed in the Descriptor pool/queue
+#define RECEIVE_DESC_SIZE   16//256 //Rx Descriptors needed in the Descriptor pool/queue
 
 #define ETHERNET_HEADER             14  //6 byte Dest addr, 6 byte Src addr, 2 byte length/type
 #define ETHERNET_CRC                 4  //Ethernet CRC