[SPARC64]: Fix compile error in irq.c

irq.c is missing the inclusion of asm/io.h, which causes
readb() and writeb() the be undefined.
Signed-off-by: Sven Hartge <hartge@ds9.argh.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc64/kernel/irq.c

@@ -27,6 +27,7 @@
 #include <asm/atomic.h>
 #include <asm/system.h>
 #include <asm/irq.h>
+#include <asm/io.h>
 #include <asm/sbus.h>
 #include <asm/iommu.h>
 #include <asm/upa.h>