dt-bindings: pinctrl: samsung: add exynos7870-wakeup-eint compatible

Exynos7870's wakeup pin controller is entirely register-compatible with
Exynos7, thus document the node for Exynos7870 appropriately.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Link: https://lore.kernel.org/r/20250301-exynos7870-pinctrl-v3-2-ba1da9d3cd2f@disroot.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Author: Kaustabh Chakraborty

Documentation/devicetree/bindings/pinctrl/samsung,pinctrl-wakeup-interrupt.yaml

@@ -40,6 +40,7 @@ properties:
       - items:
           - enum:
               - samsung,exynos5433-wakeup-eint
+              - samsung,exynos7870-wakeup-eint
               - samsung,exynos7885-wakeup-eint
               - samsung,exynos850-wakeup-eint
               - samsung,exynos8895-wakeup-eint
@@ -105,6 +106,7 @@ allOf:
             - contains:
                 enum:
                   - samsung,exynos5433-wakeup-eint
+                  - samsung,exynos7870-wakeup-eint
                   - samsung,exynos7885-wakeup-eint
                   - samsung,exynos8895-wakeup-eint
     then: