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/wan/cycx_x25.c b/drivers/net/wan/cycx_x25.c
index 2573c18..cd8cb95 100644
--- a/drivers/net/wan/cycx_x25.c
+++ b/drivers/net/wan/cycx_x25.c
@@ -84,6 +84,7 @@
 #include <linux/kernel.h>	/* printk(), and other useful stuff */
 #include <linux/module.h>
 #include <linux/string.h>	/* inline memset(), etc. */
+#include <linux/sched.h>
 #include <linux/slab.h>		/* kmalloc(), kfree() */
 #include <linux/stddef.h>	/* offsetof(), etc. */
 #include <linux/wanrouter.h>	/* WAN router definitions */