Patch from Ben Dooks

The patch does a number of updates, which are inter-dependant
on each other, for the s3c2440 support and some clean-ups for
all s3c24xx architecture in general.
1) Remove the s3c24xx_{fclk,hclk,pclk} variables, and pass
   these values to the clock core on initialisation. This
   removes the needless double copy, as only the timer code
   uses these directly (see point 4).
   Add an over-all xtal clock to the clock core
2) Add a sysdev driver to the clock code to ensure all the
   s3c2440 clocks are added if an s3c2440 is present.
3) Add the new IRQs to irq.c, and initialise them if the
   sysdev for the s3c2440 is present.
4) Change the timer code to request the timer clk and
   use it to get the frequency.
Depends on patch 2467/1
Thanks to Guillaume Gourat for the original patches that
prompted this re-write.

Signed-off-by: Ben Dooks
Signed-off-by: Russell King