[PATCH] ppc64: systemcfg is now a pointer

The following patch fixes 2 issues:
  1) use PLATFORM_LPAR bit to test if running in LPAR mode
  2) systemcfg pointer is assigned from static data in
     arch/ppc64/kernel/pacaData.c.  The file arch/ppc64/kernel/head.S
     now refers to is using the GOT binding to the pointer and hence
     must deref it.

Signed-off-by: Jimi Xenidis <jimix@watson.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>