ARM: dts: exynos: Move common Exynos4x12 definitions to exynos4x12.dtsi

ARM: dts: exynos: Move common Exynos4x12 definitions to exynos4x12.dtsi

In preparation for the re-introduction of the Exynos4212, move
their shared definitions to a separate file. Rename the pinctrl
definitions accordingly, and adapt the Exynos4412 DTSI to these
changes.

This reverts part of commit bca9085e0ae9 ("ARM: dts: exynos:
remove Exynos4212 support (dead code)").

Signed-off-by: Artur Weber <aweber.kernel@gmail.com>
Link: https://lore.kernel.org/r/20230501195525.6268-10-aweber.kernel@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>