ppc/ppc405: Change kernel load address

ppc/ppc405: Change kernel load address

The default addresses to load the kernel, fdt, initrd of AMCC boards
in U-Boot v2015.10 are :

	"kernel_addr_r=1000000\0"
	"fdt_addr_r=1800000\0"
	"ramdisk_addr_r=1900000\0"

The taihu is one of these boards, the ref405ep is not but we don't
have much information on it and both boards have a very similar
address space layout.

Also, if loaded at address 0, U-Boot will partially overwrite the
uImage because of a bug in get_ram_size() (U-Boot v2015.10) not
restoring properly the probed RAM contents and because the exception
vectors are installed in the same range. Finally, a gzipped kernel
image will be uncompressed at 0x0. These are all good reasons for not
mappping a kernel image at this address.

Change the kernel load address to match U-Boot expectations and fix
loading.

Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20211202191446.1292125-1-clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20211206103712.1866296-2-clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>