powerpc/44x: Kexec support for PPC440X chipsets

powerpc/44x: Kexec support for PPC440X chipsets

This patch adds kexec support for PPC440 based chipsets.  This work is based
on the KEXEC patches for FSL BookE.

The FSL BookE patch and the code flow could be found at the link below:

	http://patchwork.ozlabs.org/patch/49359/

Steps:

1) Invalidate all the TLB entries except the one this code is run from
2) Create a tmp mapping for our code in the other address space and jump to it
3) Invalidate the entry we used
4) Create a 1:1 mapping for 0-2GiB in blocks of 256M
5) Jump to the new 1:1 mapping and invalidate the tmp mapping

I have tested this patches on Ebony, Sequoia boards and Virtex on QEMU.

You need kexec-tools commit e8b7939b1e or newer for ppc440x support,
available at:

 git://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git

Signed-off-by: 	Suzuki Poulose <suzuki@in.ibm.com>
Cc:	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Josh Boyer <jwboyer@gmail.com>