arm64: dts: freescale: imx8mp-skov: operate SoC in nominal mode

arm64: dts: freescale: imx8mp-skov: operate SoC in nominal mode

To reduce heat generation, the Skov i.MX8MP boards should run in nominal
drive mode with a VDD_SOC voltage of 850 mV.

At this operating point, not all frequencies that are achievable with
overdrive mode are possible, so import imx8mp-nominal.dtsi to clock down
the clocks.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>