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/ns83820.c b/drivers/net/ns83820.c
index c594e19..57fd483 100644
--- a/drivers/net/ns83820.c
+++ b/drivers/net/ns83820.c
@@ -111,6 +111,7 @@
 #include <linux/compiler.h>
 #include <linux/prefetch.h>
 #include <linux/ethtool.h>
+#include <linux/sched.h>
 #include <linux/timer.h>
 #include <linux/if_vlan.h>
 #include <linux/rtnetlink.h>