On herobrine boards the keyboard backlight is controlled through the
PWM LED driver. Currently both the PWM LED node and the node for the
keyboard backlight are disabled in sc7280-herobrine.dtsi, which
requires boards with a backlit keyboard to enable both nodes. There
are no other PWM LEDs on herobrine boards besides the keyboard
backlight, delete the 'disabled' status from the keyboard backlight
node, with that boards only have to enable the 'pwmleds' node for
keyboard backlight support.

Also add a label to the 'pwmleds' node to allow board files to refer to
it with a phandle.
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220523123157.v2.1.I47ec78581907f7ef024f10bc085f970abf01ec11@changeid