arm64: dts: uniphier: Fix opp-table node name for LD20

To fix dtbs_check warning:

uniphier-ld20-akebi96.dt.yaml: opp-table0: $nodename:0: 'opp-table0' does not match '^opp-table(-[a-z0-9]+)?$'
        From schema: Documentation/devicetree/bindings/opp/opp-v2.yaml

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/20220913042321.4817-9-hayashi.kunihiko@socionext.com

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Signed-off-by: Arnd Bergmann <arnd@arndb.de>