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>

drivers/isdn/hisax/hfc_2bds0.c

@@ -11,6 +11,7 @@
  */
 
 #include <linux/init.h>
+#include <linux/sched.h>
 #include "hisax.h"
 #include "hfc_2bds0.h"
 #include "isdnl1.h"