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/isdn/hysdn/hysdn_proclog.c b/drivers/isdn/hysdn/hysdn_proclog.c
index 8991d2c..8bcae28 100644
--- a/drivers/isdn/hysdn/hysdn_proclog.c
+++ b/drivers/isdn/hysdn/hysdn_proclog.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/poll.h>
 #include <linux/proc_fs.h>
+#include <linux/sched.h>
 #include <linux/smp_lock.h>
 
 #include "hysdn_defs.h"