spi: Introduce spi_for_each_valid_cs() in order of deduplication

In order of deduplication and better maintenance introduce a new
spi_for_each_valid_cs() helper macro.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240415193340.1279360-3-andriy.shevchenko@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>