leds: pca963x: workaround group blink scaling issue

PCA9632TK part seems to incorrectly blink at ~1.3x of the programmed
rate. This patchset add a nxp,period-scale devicetree property to
adjust for this misconfiguration.

Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>