sparc64: Fix build by including linux/irq.h into time_64.c

Changeset d7e51e66 ("sparseirq: make
some func to be used with genirq") broke the build on sparc64:

arch/sparc/kernel/time_64.c: In function ‘timer_interrupt’:
arch/sparc/kernel/time_64.c:732: error: implicit declaration of function ‘kstat_incr_irqs_this_cpu’
make[1]: *** [arch/sparc/kernel/time_64.o] Error 1
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/sparc/kernel/time_64.c

@@ -36,10 +36,10 @@
 #include <linux/clocksource.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/irq.h>
 
 #include <asm/oplib.h>
 #include <asm/timer.h>
-#include <asm/irq.h>
 #include <asm/io.h>
 #include <asm/prom.h>
 #include <asm/starfire.h>