headers: remove sched.h from interrupt.h

After m68k's task_thread_info() doesn't refer to current,
it's possible to remove sched.h from interrupt.h and not break m68k!
Many thanks to Heiko Carstens for allowing this.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
diff --git a/drivers/input/serio/serport.c b/drivers/input/serio/serport.c
index b9694b6..6d345112 100644
--- a/drivers/input/serio/serport.c
+++ b/drivers/input/serio/serport.c
@@ -15,6 +15,7 @@
 
 #include <asm/uaccess.h>
 #include <linux/kernel.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/init.h>