Fix previous commit to correctly set SpiDev device cshigh property.

Author: tdicola

Adafruit_GPIO/SPI.py

@@ -43,7 +43,7 @@ def __init__(self, port, device, max_speed_hz=500000):
         self._device.max_speed_hz=max_speed_hz
         # Default to mode 0, and make sure CS is active low.
         self._device.mode = 0
-        self.cshigh = False
+        self._device.cshigh = False
 
     def set_clock_hz(self, hz):
         """Set the speed of the SPI clock in hertz.  Note that not all speeds