clk: samsung: add clock-driver for s3c2416, s3c2443 and s3c2450

The three SoCs share a common clock tree which only differs in the
existence of some special clocks.

As with all parts common to these three SoCs the driver is named
after the s3c2443, as it was the first SoC introducing this structure
and there exists no other label to describe this s3c24xx epoch.

The clock structure is built according to the manuals of the included
SoCs and might include changes in comparison to the previous clock
structure. As an example the sclk_uart gate was never handled previously
and the div_uart was made to be the clock used by the serial driver.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>