Fix a build error in drivers/mfd/ioc3.o by exporting
spurious_interrupt().

ERROR: modpost: "spurious_interrupt" [drivers/mfd/ioc3.ko] undefined!

Reported-by: kernel test robot <redacted>
Signed-off-by: Randy Dunlap <redacted>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Paul Burton <paulburton@kernel.org>
Cc: linux-mips@vger.kernel.org
---
 arch/mips/kernel/irq.c |    2 ++
 1 file changed, 2 insertions(+)

--- linux-next-20201016.orig/arch/mips/kernel/irq.c
+++ linux-next-20201016/arch/mips/kernel/irq.c

@@ -10,6 +10,7 @@
  */
 #include <linux/kernel.h>
 #include <linux/delay.h>
+#include <linux/export.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>

@@ -48,6 +49,7 @@ asmlinkage void spurious_interrupt(void)
 {
 	atomic_inc(&irq_err_count);
 }
+EXPORT_SYMBOL(spurious_interrupt);
 
 void __init init_IRQ(void)
 {