leds: Add AW20xx driver

This commit adds support for AWINIC AW20036/AW20054/AW20072 LED driver.
This driver supports following AW200XX features:
  - Individual 64-level DIM currents

Signed-off-by: Martin Kurbanov <mmkurbanov@sberdevices.ru>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20230519130403.212479-3-mmkurbanov@sberdevices.ru


Signed-off-by: Lee Jones <lee@kernel.org>