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/sungem.c b/drivers/net/sungem.c
index 305ec3d..7019a0d 100644
--- a/drivers/net/sungem.c
+++ b/drivers/net/sungem.c
@@ -38,6 +38,7 @@
 #include <linux/interrupt.h>
 #include <linux/ioport.h>
 #include <linux/in.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/delay.h>