hw/arm/pxa2xx: Set value default values for CCCR and CKEN on PXA255

The code used default values for PXA270 to configure CCCR. For PXA255,
the resulting register value is invalid (unsupported) and resulted
in a division by zero in the Linux kernel. Use default values from
datasheet instead.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Message-id: 1477361273-18888-1-git-send-email-linux@roeck-us.net
[PMM: fixed tabs-vs-spaces nit]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
