iio: dummy: iio_simple_dummy: Add newline after function-end

Fixes the following checkpatch.pl warning(s):

 CHECK: Please use a blank line after function/struct/union/enum declarations
 #46: FILE: drivers/iio/dummy/iio_simple_dummy.c:690:
  }
 +/*
 total: 0 errors, 0 warnings, 1 checks, 22 lines checked
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/dummy/iio_simple_dummy.c

@@ -689,6 +689,7 @@ static int iio_dummy_remove(struct iio_sw_device *swd)
 
 	return 0;
 }
+
 /*
  * module_iio_sw_device_driver() -  device driver registration
  *