Add initial support for dynamic frequency scaling of the main NOC
on imx8mq.

Make DDRC the parent of the NOC (using passive governor) so that the
main NOC is automatically scaled together with DDRC by default.

Support for proactive scaling via interconnect will come on top.
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Acked-by: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>