[PATCH] PPC64: large INITRD causes kernel not to boot

In PPC64 there are number of problems in arch/ppc64/boot/main.c that
prevent a kernel from making use of a large (greater than ~16MB) INITRD.
This is 64 bit architecture and really large INITRD images should be
possible.

Simply put the existing code has a fixed reservation (claim) address and
once the kernel plus initrd image are large enough to pass this address
all sorts of bad things occur. The fix is the dynamically establish the
first claim address above the loaded kernel plus initrd (plus some
"padding" and rounding). If PROG_START is defined this will be used as
the minimum safe address - currently known to be 0x01400000 for the
firmwares tested so far.

Signed-off-by: Mark Bellon <mbellon@mvista.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>