arm64: dts: exynos: use dedicated wake-up pinctrl compatible in Exynos850

Older Samsung Exynos SoC pin controller nodes (Exynos3250, Exynos4,
Exynos5, Exynos5433) with external wake-up interrupts, expected to have
one interrupt for multiplexing these wake-up interrupts.  Also they
expected to have exactly one pin controller capable of external wake-up
interrupts.

It seems however that newer ARMv8 Exynos SoC like Exynos850 and
ExynosAutov9 have differences:
1. No multiplexed external wake-up interrupt, only direct,
2. More than one pin controller capable of external wake-up interrupts.

Use dedicated Exynos850 compatible for its external wake-up interrupts
controller to indicate the differences.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20220111201722.327219-21-krzysztof.kozlowski@canonical.com