clk: samsung: add plls used by the early s3c24xx cpus

The manuals do not give them explicit names like in later socs, so more
generic names with a s3c2410-prefix were used for them.

As it was common to do so in the previous implementation, functionality
to change the pll rate is already included.

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