iio: frequency: adf4377: Switch to device_property_match_property_string()

Replace open coded device_property_match_property_string().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230808162800.61651-4-andriy.shevchenko@linux.intel.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>