[ARM] S3C2443: Add prediv clk and fix setting of h and p clocks

[ARM] S3C2443: Add prediv clk and fix setting of h and p clocks

Update the S3C2443 clock support to add the prediv clock
that is sourced via a divider from msysclk. Also fix the
setting of p and h clocks from this prediv clock.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>