ARM: dts: at91: align LED node names with dtschema

The node names should be generic and DT schema expects certain pattern:

  at91-sama5d2_ptc_ek.dtb: leds: 'blue', 'green', 'red' do not match any of the regexes: '(^led-[0-9a-f]$|led)', 'pinctrl-[0-9]+'

Link: https://lore.kernel.org/r/20221125144131.477089-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>