clk: samsung: Allow compile testing of Exynos, S3C64xx and S5Pv210

So far all Exynos, S3C64xx and S5Pv210 clock units were selected by
respective SOC/ARCH Kconfig option.  On a kernel built for selected
SoCs, this allowed to build only limited set of matching clock drivers.
However compile testing was not possible in such case as Makefile object
depends on SOC/ARCH option.

Add separate Kconfig options for each of them to be able to compile
test.

Link: https://lore.kernel.org/r/20201119164509.754851-1-krzk@kernel.org


Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>