clk: samsung: Add clock driver for S3C64xx SoCs

This patch adds new, Common Clock Framework-based clock driver for Samsung
S3C64xx SoCs. The driver is just added, without actually letting the
platforms use it yet, since this requires more intermediate steps.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>