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/net/wireless/ipw2x00/ipw2200.c

@@ -30,6 +30,7 @@
 
 ******************************************************************************/
 
+#include <linux/sched.h>
 #include "ipw2200.h"