clk: samsung: add pll_6552 variant for s3c2416

According to the manual s3c2416 and s3c2450 use a pll 6552 and 6553
and while the pll_6553 matches exactly the one already implemented
the pll_6552 differs to the one from the s3c64xx series.

The change is solely in the bit locations of the mdiv and pdiv values.
All calculations are the same for both implementatons and even the
proposed divider-values for specific frequencies in the manuals are
the same.

Therefore implement a variant that simply uses the changed bit
locations if necessary.

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