pinctrl: cy8c95x0: Extract cy8c95x0_set_mode() helper

The code in newly introduced cy8c95x0_set_mode() helper may be
used later on by another function.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221010125221.28275-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>