[PATCH] Change address of ppc64 initial segment table

On ppc64 machines with segment tables, CPU0's segment table is at a
fixed address, currently 0x9000.  This patch moves it to the free
space at 0x6000, just below the fwnmi data area.  This saves 8k of
space in vmlinux and the runtime kernel image.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>