leds: centralize definition of "default-state" property

Four different drivers define the "default-state" property.
Move this into the common.txt common LEDs properties.

Cc: devicetree@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>