added mssing default value for sim refclk_200
added mssing default value for sim refclk_200

Signed-off-by: Reiner Rieke <47c589b7af30848391909c6b73d75bdd7aee51c7@de.ibm.com>

open-power/snap,open-power/snap,open-power/snap,open-power/snap,open-power/snap