boards/arduino-mkrzero: fix on-board LED and common jlink conf

Author: aabadie

boards/arduino-mkrzero/Makefile.include

@@ -1,5 +1,9 @@
 USEMODULE += arduino-mkr-common
 
+ifeq ($(PROGRAMMER),jlink)
+  export MKR_JLINK_DEVICE = atsamd21
+endif
+
 include $(RIOTBOARD)/arduino-mkr-common/Makefile.include
 
 # add arduino-mkrzero include path

boards/arduino-mkrzero/include/board.h

@@ -57,7 +57,7 @@ extern "C" {
 #define LED0_PIN            GPIO_PIN(PB, 8)
 
 #define LED_PORT            PORT->Group[PB]
-#define LED0_MASK           (1 << 20)
+#define LED0_MASK           (1 << 8)
 
 #define LED0_ON             (LED_PORT.OUTSET.reg = LED0_MASK)
 #define LED0_OFF            (LED_PORT.OUTCLR.reg = LED0_MASK)