dt-bindings: leds: ROHM BD71282 PMIC LED driver

Document ROHM BD71828 PMIC LED driver device tree bindings.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Lee Jones <lee.jones@linaro.org>