RP2 DVP PIO driver: Disable DMA in active()

Fixes #28

Author: sfe-SparkFro

cv2_drivers/cameras/dvp_rp2_pio.py

@@ -76,6 +76,9 @@ def active(self, active = None):
         if active == None:
             return self.sm.active()
 
+        # Disable the DMA, the VSYNC handler will re-enable it when needed
+        self.dma.active(False)
+
         # Set the active state of the state machine
         self.sm.active(active)