Ethernet: use CS pin constant in ARC architecture

Author: cmaglie

libraries/Ethernet/src/utility/w5100.h

@@ -344,9 +344,9 @@ class W5x00Class {
 #if !defined(SPI_HAS_EXTENDED_CS_PIN_HANDLING)
   #define SPI_ETHERNET_SETTINGS SPISettings(14000000, MSBFIRST, SPI_MODE0)
   #if defined(__ARDUINO_ARC__)
-    inline static void initSS()  { pinMode(10, OUTPUT);    }
-    inline static void setSS()   { digitalWrite(10, LOW);  }
-    inline static void resetSS() { digitalWrite(10, HIGH); }
+    inline static void initSS()  { pinMode(ETHERNET_SHIELD_SPI_CS, OUTPUT);    }
+    inline static void setSS()   { digitalWrite(ETHERNET_SHIELD_SPI_CS, LOW);  }
+    inline static void resetSS() { digitalWrite(ETHERNET_SHIELD_SPI_CS, HIGH); }
   #else
     inline static void initSS()  { pinMode(ETHERNET_SHIELD_SPI_CS, OUTPUT); }
     inline static void setSS()   { *portOutputRegister(digitalPinToPort(ETHERNET_SHIELD_SPI_CS)) &= ~digitalPinToBitMask(ETHERNET_SHIELD_SPI_CS); }