powerpc: Add irq accounting for watchdog interrupts

This adds an irq counter for the watchdog soft-NMI. This interrupt
only fires when interrupts are soft-disabled, so it will not
increment much even when the watchdog is running. However it's
useful for debugging and sanity checking.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/include/asm/hardirq.h b/arch/powerpc/include/asm/hardirq.h
index 64b73b0..c97603d 100644
--- a/arch/powerpc/include/asm/hardirq.h
+++ b/arch/powerpc/include/asm/hardirq.h
@@ -13,6 +13,9 @@
 	unsigned int spurious_irqs;
 	unsigned int hmi_exceptions;
 	unsigned int sreset_irqs;
+#ifdef CONFIG_PPC_WATCHDOG
+	unsigned int soft_nmi_irqs;
+#endif
 #ifdef CONFIG_PPC_DOORBELL
 	unsigned int doorbell_irqs;
 #endif