hw/riscv: Support to load DTB after 3GB memory on 64-bit system.

Larger initrd image will overlap the DTB at 3GB address. Since 64-bit
system doesn't have 32-bit addressable issue, we just load DTB to the end
of dram in 64-bit system.

Signed-off-by: Jim Shu <jim.shu@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20241120153935.24706-2-jim.shu@sifive.com>
[ Changes by AF
 -  Store fdt_load_addr_hi32 in the reset vector
]
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

hw/riscv/virt.c

@@ -1492,7 +1492,7 @@ static void virt_machine_done(Notifier *notifier, void *data)
 
     fdt_load_addr = riscv_compute_fdt_addr(memmap[VIRT_DRAM].base,
                                            memmap[VIRT_DRAM].size,
-                                           machine);
+                                           machine, &s->soc[0]);
     riscv_load_fdt(fdt_load_addr, machine->fdt);
 
     /* load the reset vector */