Input: gpio_decoder - replace custom loop by gpiod_get_array_value_cansleep()

Input: gpio_decoder - replace custom loop by gpiod_get_array_value_cansleep()

There is a custom loop that repeats parts of gpiod_get_array_value_cansleep().
Use that in conjunction with bitmap API to make code shorter and easier to
follow.

With this done, add an upper check for amount of GPIOs given based on
the driver's code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20251113154616.3107676-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>