clk: exynos: prepare for multiplatform

The new common clock drivers for exynos are using compile
time constants and soc_is_exynos* macros to provide backwards
compatibility for pre-DT systems, which is not possible with
multiplatform kernels. This moves all the necessary
information back into platform code and removes the mach/*
header inclusions.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Mike Turquette <mturquette@linaro.org>