drivers/stmpe811: reset the FIFO queue after read

The FIFO queue has to be reset after reading one touch position. Otherwise new touch positions are processed with a delay if the rate of calling the function to read the FIFO is slower than the rate at which the FIFO is filled. The reason for this is that with each call of this function always only the oldest touch position is read value by value from the FIFO. Gestures, for example, can't be implemented with such a behavior

drivers/stmpe811/stmpe811.c

@@ -339,6 +339,14 @@ int stmpe811_read_touch_position(stmpe811_t *dev, stmpe811_touch_position_t *pos
     }
 #endif
 
+    /* Reset the FIFO, otherwise new touch data will be processed with a delay
+     * if the rate of calling this function to read the FIFO is slower than
+     * the rate at which the FIFO is filled. The reason for this is that with
+     * each call of this function only the oldest touch data is read
+     * value by value from the FIFO. Gestures, for example, can't be
+     * implemented with such a behavior. */
+    _reset_fifo(dev);
+
     /* Release device bus */
     _release(dev);