[S390] irq: have detailed statistics for interrupt types

Up to now /proc/interrupts only has statistics for external and i/o
interrupts but doesn't split up them any further.
This patch adds a line for every single interrupt source so that it
is possible to easier tell what the machine is/was doing.
Part of the output now looks like this;

           CPU0       CPU2       CPU4
EXT:       3898       4232       2305
I/O:        782        315        245
CLK:       1029       1964        727   [EXT] Clock Comparator
IPI:       2868       2267       1577   [EXT] Signal Processor
TMR:          0          0          0   [EXT] CPU Timer
TAL:          0          0          0   [EXT] Timing Alert
PFL:          0          0          0   [EXT] Pseudo Page Fault
[...]
NMI:          0          1          1   [NMI] Machine Checks

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index fe5701e..839b16d 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -10,6 +10,7 @@
  *    Copyright (C) 1995  Linus Torvalds
  */
 
+#include <linux/kernel_stat.h>
 #include <linux/perf_event.h>
 #include <linux/signal.h>
 #include <linux/sched.h>
@@ -543,6 +544,7 @@
 	struct task_struct *tsk;
 	__u16 subcode;
 
+	kstat_cpu(smp_processor_id()).irqs[EXTINT_PFL]++;
 	/*
 	 * Get the external interruption subcode & pfault
 	 * initial/completion signal bit. VM stores this