arm: Don't set freq properties on CMSDK timer, dualtimer, watchdog, ARMSSE

Remove all the code that sets frequency properties on the CMSDK
timer, dualtimer and watchdog devices and on the ARMSSE SoC device:
these properties are unused now that the devices rely on their Clock
inputs instead.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20210128114145.20536-24-peter.maydell@linaro.org
Message-id: 20210121190622.22000-24-peter.maydell@linaro.org