hw/ppc: set machine->fdt in bamboo_load_device_tree()

hw/ppc: set machine->fdt in bamboo_load_device_tree()

This will enable support for 'dumpdtb' QMP/HMP command for the bamboo
machine.

Setting machine->fdt requires a MachineState pointer to be used inside
bamboo_load_device_tree(). Let's change the function to receive this
pointer from the caller. 'ramsize' and 'kernel_cmdline' can be retrieved
directly from the 'machine' pointer.

Cc: Cédric Le Goater <clg@kaod.org>
Reviewed-by: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20220926173855.1159396-9-danielhb413@gmail.com>