[ARM] 4986/1: S3C24XX: Simtec machines need UCLK as parent to DCLK

All current Simtec designs source the DCLK outputs from
the UPLL. This means the DCLK's parent must be set to UPLL
so that anything enabling and disabling an UPLL sourced
clock does not shutdown the DCLK due to missing open counts.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>