staging: ad7606_core: Fix checkpatch warning

Fix the checkpatch complaint regarding unnecessary line continuation.
  WARNING: Avoid unnecessary line continuations
  linux-sunxi#143: FILE: ad7606_core.c:143:

Signed-off-by: Sören Brinkmann <soeren.brinkmann@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/adc/ad7606_core.c

@@ -140,7 +140,7 @@ static ssize_t ad7606_store_range(struct device *dev,
 	return count;
 }
 
-static IIO_DEVICE_ATTR(in_voltage_range, S_IRUGO | S_IWUSR, \
+static IIO_DEVICE_ATTR(in_voltage_range, S_IRUGO | S_IWUSR,
 		       ad7606_show_range, ad7606_store_range, 0);
 static IIO_CONST_ATTR(in_voltage_range_available, "5000 10000");