Instead of passing the MSF2 SoC an integer property specifying the
CPU clock rate, pass it a Clock instead.  This lets us wire that
clock up to the armv7m object.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alexandre Iooss <erdnaxe@crans.org>
Message-id: 20210812093356.1946-20-peter.maydell@linaro.org