ARM: S3C64XX: Compress s3c6400-clock.c code

The individually named clocks are all static to the code
and thus can be compressed into a single array and then
the array can be referenced. This removes the need for
a seperate array of pointers to clocks.

Fix a minor problem of re-initialising the pointers in
s3c6400_set_clksrc() as this is also called by the cpufreq
code. Move these initialisations to the code that does the
registration.

Based on Harald Welte's original clock changes patch.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>