arm64: dts: imx8mn-ddr4-evk: Remove unneeded PMIC pin configuration

The pin configuration for PMIC interrupt is already set by
imx8mn-evk.dtsi with exactly the same values.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>