Support copying of kernel tagged list (atags) in the decompressor.

This is needed to hardboot kexec a kernel with a new tags list (including a
new kernel command line), since the new atags would otherwise be lost with
the limited kernel memory mapping.  Without this patch, a hardboot-kexec'd
kernel uses the atags provided by the bootloader.

Change-Id: I66332aa91afae651bbfbd6a46dfca7db11d79861
Signed-off-by: Steven Barker <lilstevie@lilstevie.geek.nz>
Enable caching and buffering for all of physical RAM in the decompressor.

Old method is to enable caching and buffering only for the 256 MB at the
start of the decompressor image.  This makes a hardboot-kexec'd kernel very
slow to decompress since the decompressor is located far above the kernel
destination.  This patch reduces boot time from 35 to 8 seconds.

Conflicts:

	arch/arm/mach-s5pv210/include/mach/memory.h

Change-Id: I3f01867414e212598c8138119b016a38d93c573c
Signed-off-by: Steven Barker <lilstevie@lilstevie.geek.nz>