clk: exynos: Add Exynos850 clock driver

Heavily influenced by its Linux kernel counterpart. It's implemented on
top of recently added Samsung CCF clock framework API. For now only UART
leaf clocks are implemented, along with all preceding clocks in CMU_TOP
and CMU_PERI. The UART baud clock is required in the serial driver, to
get its rate for the consequent baud rate calculation.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Chanho Park <chanho61.park@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
diff --git a/drivers/clk/exynos/Kconfig b/drivers/clk/exynos/Kconfig
index eb0efa9..85ce9d6 100644
--- a/drivers/clk/exynos/Kconfig
+++ b/drivers/clk/exynos/Kconfig
@@ -15,4 +15,11 @@
 	  This enables common clock driver support for platforms based
 	  on Samsung Exynos7420 SoC.
 
+config CLK_EXYNOS850
+	bool "Clock driver for Samsung's Exynos850 SoC"
+	select CLK_CCF
+	help
+	  This enables common clock driver support for platforms based
+	  on Samsung Exynos850 SoC.
+
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