dt-bindings: pinctrl: samsung: Add exynos990-pinctrl compatible

Add a dedicated compatible for the exynos990-pinctrl node.

Signed-off-by: Igor Belwon <igor.belwon@mentallysanemainliners.org>
Link: https://lore.kernel.org/r/20241016154838.64515-2-igor.belwon@mentallysanemainliners.org


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