Fix SPI pin warnings.

blockly/generators/arduino/spi.js

@@ -66,11 +66,10 @@ Blockly.Arduino['spi_transfer'] = function(block) {
   Blockly.Arduino.addSetup('spi_begin', spiId + '.begin();', false);
 
   // Reserve SPI pins MOSI, MISO, and SCK
-  for (var i = 0; i < Blockly.Arduino.Boards.selected.spiPins.length; i++) {
-    Blockly.Arduino.reservePin(block,
-        Blockly.Arduino.Boards.selected.spiPins[i][1],
-        Blockly.Arduino.PinTypes.SPI,
-        'SPI ' + Blockly.Arduino.Boards.selected.spiPins[i][0]);
+  var spiPins = Blockly.Arduino.Boards.selected.spiPins[spiId];
+  for (var i = 0; i < spiPins.length; i++) {
+    Blockly.Arduino.reservePin(block, spiPins[i][1],
+        Blockly.Arduino.PinTypes.SPI, 'SPI ' + spiPins[i][0]);
   }
 
   // Configure the Slave Select as a normal output if a pin is used