hw/riscv/virt.c: do create_fdt() earlier, add finalize_fdt()

hw/riscv/virt.c: do create_fdt() earlier, add finalize_fdt()

Commit 49554856f0 fixed a problem, where TPM devices were not appearing
in the FDT, by delaying the FDT creation up until virt_machine_done().
This create a side effect (see gitlab #1925) - devices that need access
to the '/chosen' FDT node during realize() stopped working because, at
that point, we don't have a FDT.

This happens because our FDT creation is monolithic, but it doesn't need
to be. We can add the needed FDT components for realize() time and, at
the same time, do another FDT round where we account for dynamic sysbus
devices.  In other words, the problem fixed by 49554856f0 could also be
fixed by postponing only create_fdt_sockets() and its dependencies,
leaving everything else from create_fdt() to be done during init().

Split the FDT creation in two parts:

- create_fdt(), now moved back to virt_machine_init(), will create FDT
  nodes that doesn't depend on additional (dynamic) devices from the
  sysbus;

- a new finalize_fdt() step is added, where create_fdt_sockets() and
  friends is executed, accounting for the dynamic sysbus devices that
  were added during realize().

This will make both use cases happy: TPM devices are still working as
intended, and devices such as 'guest-loader' have a FDT to work on
during realize().

Fixes: 49554856f0 ("riscv: Generate devicetree only after machine initialization is complete")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1925
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231110172559.73209-1-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>