leds: pca995x: Add support for PCA995X chips

The PCA995x chips are I2C controlled LED drivers. Each chip has
up to 16 outputs, each one with an individual 8-bit resolution
PWM for brightness control.

Signed-off-by: Isai Gaspar <isaiezequiel.gaspar@nxp.com>
Signed-off-by: Marek Vasut <marex@denx.de> # Basically rewrite the driver
Link: https://lore.kernel.org/r/20230713163516.21644-2-marex@denx.de


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