arm64: dts: imx8mp-phycore-som: Remove LDO2 and LDO4 pmic nodes

We do not touch LDO2 and LDO4 in linux as they are bypassed.
So remove them completely from device tree.

Signed-off-by: Teresa Remmet <t.remmet@phytec.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>