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/net/forcedeth.c b/drivers/net/forcedeth.c
index 0a1c2bb..e1da466 100644
--- a/drivers/net/forcedeth.c
+++ b/drivers/net/forcedeth.c
@@ -49,6 +49,7 @@
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/delay.h>
+#include <linux/sched.h>
 #include <linux/spinlock.h>
 #include <linux/ethtool.h>
 #include <linux/timer.h>