leds:pca963x: Update for PCA9635 and correct statement about MODE2 OUTDRV default

mention support for 16 LED PCA9635 chip

the default of MODE2's OUTDRV was incorrectly stated

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Bryan Wu <cooloney@gmail.com>