[S390] ipc: call generic sys_ipc demultiplexer

Call generic IPC demultiplexer instead of having a nearly identical
s390 variant. Also make sure that native and compat handling now have
the same behaviour.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/unistd.h b/arch/s390/include/asm/unistd.h
index 58de4c9..8a8008f 100644
--- a/arch/s390/include/asm/unistd.h
+++ b/arch/s390/include/asm/unistd.h
@@ -398,6 +398,7 @@
 #define __ARCH_WANT_SYS_SIGNAL
 #define __ARCH_WANT_SYS_UTIME
 #define __ARCH_WANT_SYS_SOCKETCALL
+#define __ARCH_WANT_SYS_IPC
 #define __ARCH_WANT_SYS_FADVISE64
 #define __ARCH_WANT_SYS_GETPGRP
 #define __ARCH_WANT_SYS_LLSEEK