[S390] claw: add support for irq statistics

Add support for CLAW I/O interrupt statistics in /proc/interrupts.

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/irq.h b/arch/s390/include/asm/irq.h
index 6a455b8..2d5943c 100644
--- a/arch/s390/include/asm/irq.h
+++ b/arch/s390/include/asm/irq.h
@@ -23,6 +23,7 @@
 	IOINT_TAP,
 	IOINT_VMR,
 	IOINT_LCS,
+	IOINT_CLW,
 	NMI_NMI,
 	NR_IRQS,
 };