The 44x code (which is shared by 47x) assumes the available physical memory
begins at 0x00000000.  This is not necessarily the case in an AMP
environment.

Support CONFIG_RELOCATABLE for 476 in order to allow the kernel to be
loaded into a higher memory range.
Signed-off-by: NTony Breeds <tony@bakeyournoodle.com>
Signed-off-by: NDave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>