clk/samsung: add support for multiple clock providers

Samsung CCF helper functions do not provide support to
register multiple Clock Providers for a given SoC. Due to
this limitation, SoC platforms are not able to use these
helpers for registering multiple clock providers and are
forced to bypass this layer.

This layer is modified accordingly to enable the support
for multiple clock providers.

Clock file for exynos4, exynos5250, exynos5420, exynos5440,
S3c64xx, S3c24xx are also modified as per changed helper functions.

Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
[t.figa: Modified s3c2410 clock driver as well]
Signed-off-by: Tomasz Figa <t.figa@samsung.com>