arm64: dts: imx8mm: Init rates and parents configs for clocks

Add the initial configuration for clocks that need default parent and rate
setting. This is based on the vendor tree clock provider parents and rates
configuration except this is doing the setup in dts rather than using clock
consumer API in a clock provider driver.

Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Acked-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>