dt-bindings: clock: samsung,exynos: add Exynos4212 clock compatible

Support for the Exynos4212 SoC was originally dropped as there were
no boards using it. We will be adding a device that uses it, so add
back the relevant compatible.

Signed-off-by: Artur Weber <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

Documentation/devicetree/bindings/clock/samsung,exynos-clock.yaml

···
           - samsung,exynos3250-cmu-dmc
           - samsung,exynos3250-cmu-isp
           - samsung,exynos4210-clock
+          - samsung,exynos4212-clock
           - samsung,exynos4412-clock
           - samsung,exynos5250-clock
       - items: