ARM: dts: aspeed: fix PCA95xx GPIO expander properties on Portwell

The PCA95xx GPIO expander requires GPIO controller properties to operate
properly.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20210212162640.66677-1-krzk@kernel.org

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