hw/arm: fsl-imx8mp: Don't call qdev_get_machine in soc init

hw/arm: fsl-imx8mp: Don't call qdev_get_machine in soc init

Calling qdev_get_machine() in the soc_init function would result in
the following assert

    ../hw/core/qdev.c:858: qdev_get_machine: Assertion `dev' failed.

when trying to run

    ./qemu-system-aarch64 -S -display none -M virt -device fsl-imx8mp,help

as the machine wasn't created yet. We call qdev_get_machine() to obtain
the number of CPUs in the machine. So instead of initialising the CPUs in
the SoC init let's instead do it in the realise where the machine
will exist.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20260312043158.4191378-6-alistair.francis@wdc.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>