[PATCH] powerpc: Fix merged ipcbuf.h

Oops, when merging ipcbuf.h, I forgot that 'u64' can't be used in
user-visible headers.  This patch corrects the problem, replacing the
unused fields with an array of four __u32s.

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