Merge pull request #7549 from TomoYamanaka/improve_ether

Revise heap and stack size for Ethernet of GR-PEACH

Author: Cruz Monrreal

features/lwipstack/mbed_lib.json

@@ -127,6 +127,12 @@
         },
         "EFM32GG11-STK3701": {
             "mem-size": 36560
+        },
+        "RZ_A1_EMAC": {
+            "tcpip-thread-stacksize": 1328,
+            "default-thread-stacksize": 640,
+            "ppp-thread-stacksize": 896,
+            "mem-size": 51200
         }
     }
 }