consolidate compat lookup_dcookie()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/powerpc/include/asm/systbl.h b/arch/powerpc/include/asm/systbl.h
index 634db7d..afef04d 100644
--- a/arch/powerpc/include/asm/systbl.h
+++ b/arch/powerpc/include/asm/systbl.h
@@ -239,7 +239,7 @@
 SYSCALL(set_tid_address)
 SYSX_SPU(sys_fadvise64,ppc32_fadvise64,sys_fadvise64)
 SYSCALL(exit_group)
-SYSX(sys_lookup_dcookie,ppc32_lookup_dcookie,sys_lookup_dcookie)
+COMPAT_SYS(lookup_dcookie)
 SYSCALL_SPU(epoll_create)
 SYSCALL_SPU(epoll_ctl)
 SYSCALL_SPU(epoll_wait)