Merge pull request arduino#125 from GMagician/Fix-analogInputToDigitalPin

Fix analogInputToDigitalPin for Grand Central M4

Author: ladyada

variants/grand_central_m4/variant.h

@@ -61,7 +61,7 @@ extern "C"
 #define NUM_DIGITAL_PINS     (53u)
 #define NUM_ANALOG_INPUTS    (16u)
 #define NUM_ANALOG_OUTPUTS   (2u)
-#define analogInputToDigitalPin(p)  ((p < 6u) ? (p) + 14u : -1)
+#define analogInputToDigitalPin(p) ((p < 8) ? 67 + (p) : (p < 16) ? 54 + (p) - 8 : (p < 18) ? 12 + (p) - 16 : (p == 18) ? 9 : -1)
 
 #define digitalPinToPort(P)        ( &(PORT->Group[g_APinDescription[P].ulPort]) )
 #define digitalPinToBitMask(P)     ( 1 << g_APinDescription[P].ulPin )