clk: samsung: Remove support for Exynos4212 SoCs in Exynos CLKOUT driver

Support for Exynos4212 SoCs has been removed by commit bca9085e ("ARM:
dts: exynos: remove Exynos4212 support (dead code)"), so there is no need
to keep remaining dead code related to this SoC version.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>