clocksource/drivers/exynosy: Depend on sub-architecture for Exynos MCT and Samsung PWM

clocksource/drivers/exynosy: Depend on sub-architecture for Exynos MCT and Samsung PWM

The Exynos MCT and Samsung PWM Timer clocksource drivers are not usable
on anything else than Samsung Exynos, S3C or S5P SoC platforms.  These
are integral parts of a SoC.  Even though the drivers are not user
selectable, still document the hardware architecture explicitly with
depends on ARCH_EXYNOS and others.  This also serves a purpose of
documenting use-case, if someone ever wonders whether to select the
driver for his platform.  No functional change, because drivers are
already selected by the platform described in depends. We follow similar
approach also for other SoC-specific drivers.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211021063500.39314-1-krzysztof.kozlowski@canonical.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>