drivers: led: pca9633: add support for multiple devices

PCA9633 driver does not cunnetly support multiple devices.
Updated the driver to use DT_INST_FOREACH_STATUS_OKAY to
configure all devices defined in the device tree.
Convert driver to use `i2c_dt_spec` helpers.

Fixes #40076

Signed-off-by: Daniel N. Hansten <dnh2000@gmail.com>