Merge pull request #110 from caternuson/iss109

Init HW SPI members

Author: caternuson

Adafruit_SPIDevice.h

@@ -116,8 +116,8 @@ class Adafruit_SPIDevice {
 
 private:
 #ifdef BUSIO_HAS_HW_SPI
-  SPIClass *_spi;
-  SPISettings *_spiSetting;
+  SPIClass *_spi = nullptr;
+  SPISettings *_spiSetting = nullptr;
 #else
   uint8_t *_spi = nullptr;
   uint8_t *_spiSetting = nullptr;