hw/arm: collie: Store boot info in the machine state

arm_load_kernel() keeps a pointer to the boot info struct for the
lifetime of the VM, so the struct logically belongs to the machine
rather than to a file scoped static object.

Move the boot info into the existing CollieMachineState.

As in the xlnx-zcu102 and raspi machines, the boot info belongs to
the machine rather than to a static object:

4d1ac883a7 ("hw/arm: xlnx-zcu102: Move arm_boot_info into XlnxZCU102")
0f15c6e338 ("hw/arm/raspi: Move arm_boot_info structure to RaspiMachineState")

Signed-off-by: Bin Meng <bin.meng@processmission.com>
Message-id: 20260816131300.51799-5-bin.meng@processmission.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>