Amend compile time check to include GIGA.

Author: aentinger

libraries/Arduino_CAN/src/Arduino_CAN.h

@@ -24,8 +24,8 @@
  * COMPILE TIME CHECKS
  **************************************************************************************/
 
-#if !(defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_PORTENTA_H7_M4))
-# error "CAN only available on Arduino Portenta H7 (of all ArduinoCore-mbed enabled boards)."
+#if !(defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_PORTENTA_H7_M4) || defined(ARDUINO_GIGA))
+# error "CAN only available on Arduino Portenta H7 and Arduino Giga (of all ArduinoCore-mbed enabled boards)."
 #endif
 
 /**************************************************************************************