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

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

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