clocksource/drivers/h8300_timer8: Remove unused headers

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
diff --git a/drivers/clocksource/h8300_timer8.c b/drivers/clocksource/h8300_timer8.c
index 35b0e8f..62a7f8c 100644
--- a/drivers/clocksource/h8300_timer8.c
+++ b/drivers/clocksource/h8300_timer8.c
@@ -8,21 +8,16 @@
  */
 
 #include <linux/errno.h>
-#include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
-#include <linux/slab.h>
 #include <linux/clockchips.h>
-#include <linux/module.h>
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 
-#include <asm/irq.h>
-
 #define _8TCR	0
 #define _8TCSR	2
 #define TCORA	4