clk: samsung: Add initial Exynos7885 clock driver

This is an initial implementation adding basic clocks, such as UART,
USI, I2C, WDT, ect. and their parent clocks. It is heavily based on the
Exynos850 clock driver at 'drivers/clk/samsung/clk-exynos850.c' which
was made by Sam Protsenko, thus the copyright and author lines were
kept.

Bus clocks are enabled by default as well to avoid hangs while trying to
access CMU registers.

Only the parts of CMU_TOP needed for CMU_CORE and CMU_PERI, a bit of
CMU_CORE, and most of CMU_PERI is implemented as of now.

Signed-off-by: David Virag <virag.david003@gmail.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211206153124.427102-7-virag.david003@gmail.com