iio: frequency: ad9523: fix implicit variable macros

iio: frequency: ad9523: fix implicit variable macros

The macros AD9523_CLK_DIST_DIV_PHASE_REV(x) and
AD9523_CLK_DIST_DIV_REV(x) implicitly relied on the variable named 'ret'
instead of using passed argument '(x)'. Update the macros to explicitly
use the argument '(x)' for their operations.

This also resolves the following checkpatch.pl warning: Argument '(x)'
is not used in function-like macro.

Signed-off-by: Bhargav Joshi <rougueprince47@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>