Adding more available ADC channels for SAMD21J18

Signed-off-by: Thibaut VIARD <aethaniel@sam-geek.org>

cores/arduino/WVariant.h

@@ -37,6 +37,10 @@ typedef enum _EAnalogChannel
   ADC_Channel5=5,
   ADC_Channel6=6,
   ADC_Channel7=7,
+#if defined __SAMD21J18A__
+  ADC_Channel8=8,
+  ADC_Channel9=9,
+#endif // __SAMD21J18A__
   ADC_Channel10=10,
   ADC_Channel11=11,
 #if defined __SAMD21J18A__
@@ -44,7 +48,7 @@ typedef enum _EAnalogChannel
   ADC_Channel13=13,
   ADC_Channel14=14,
   ADC_Channel15=15,
-#endif
+#endif // __SAMD21J18A__
   ADC_Channel16=16,
   ADC_Channel17=17,
   ADC_Channel18=18,
@@ -83,7 +87,7 @@ typedef enum _ETCChannel
   TC6_CH1  = (6<<8)|(1),
   TC7_CH0  = (7<<8)|(0),
   TC7_CH1  = (7<<8)|(1),
-#endif
+#endif // __SAMD21J18A__
 } ETCChannel ;
 
 extern const void* g_apTCInstances[TCC_INST_NUM+TC_INST_NUM] ;
@@ -123,7 +127,7 @@ typedef enum _EPWMChannel
   PWM6_CH1=TC6_CH1,
   PWM7_CH0=TC7_CH0,
   PWM7_CH1=TC7_CH1,
-#endif
+#endif // __SAMD21J18A__
 } EPWMChannel ;
 
 typedef enum _EPortType