ARM: S3C64XX: Cleanup common init code in s3c6400-clock.c

Remove the four fields from clksrc_clk.clk which are always the same
and init them when the clock is registered. This helps remove the amount
of repeated code.

This is a re-work of Harald Welte's clock changes for the latest kernel.

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