[ARM] 4791/1: S3C2412: Make fclk a parent of msysclk

In the S3C2412 fclk is derived from msysclk, not straight from
the MPLL output. Set clk_f.parent appropriately.

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