Fairly trivial PPC64 cleanup.  This patch makes the ppc64 INIT_THREAD
#define use C99 initializers, which will make it less likely to get broken
if we need to change thread_struct.
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>