imx8-ss-vpu only contained imx8qxp IRQ numbers, only mu2_m0 uses the
correct imx8qm IRQ number, as imx8qxp lacks this MU.
Fix this by providing imx8qm IRQ numbers in the main imx8-ss-vpu.dtsi
and override the IRQ numbers in SoC-specific imx8qxp-ss-vpu.dtsi, similar
to reg property for VPU core devices.