ARM: dts: at91: Fix schema warnings for pwm-leds

ARM: dts: at91: Fix schema warnings for pwm-leds

The node names for devices using the pwm-leds driver follow a certain
naming scheme (now).  Parent node name is not enforced, but recommended
by DT project.

  DTC     arch/arm/boot/dts/at91-kizbox2-2.dt.yaml
  CHECK   arch/arm/boot/dts/at91-kizbox2-2.dt.yaml
/home/alex/build/linux/arch/arm/boot/dts/at91-kizbox2-2.dt.yaml: pwm_leds: 'blue', 'green', 'red' do not match any of the regexes: '^led(-[0-9a-f]+)?$', 'pinctrl-[0-9]+'
        From schema: /home/alex/src/linux/leds/Documentation/devicetree/bindings/leds/leds-pwm.yaml
  DTC     arch/arm/boot/dts/at91-kizbox3-hs.dt.yaml
  CHECK   arch/arm/boot/dts/at91-kizbox3-hs.dt.yaml
/home/alex/build/linux/arch/arm/boot/dts/at91-kizbox3-hs.dt.yaml: pwm_leds: 'blue', 'green', 'red', 'white' do not match any of the regexes: '^led(-[0-9a-f]+)?$', 'pinctrl-[0-9]+'
        From schema: /home/alex/src/linux/leds/Documentation/devicetree/bindings/leds/leds-pwm.yaml

(Warnings above are for armv7 only, armv5 would produce similar warnings.)

Signed-off-by: Alexander Dahl <post@lespocky.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20201005203451.9985-6-post@lespocky.de