arm64: dts: intel: socfpga_agilex_socdk: align LED node names with dtschema

Align the LED node names with dtschema to silence dtbs_check warnings
like:

    leds: 'hps0', 'hps1', 'hps2' do not match any of the regexes: '(^led-[0-9a-f]$|led)', 'pinctrl-[0-9]+'

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>