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/rtc/interface.c b/drivers/rtc/interface.c
index 4cdb31a..a0c8162 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -12,6 +12,7 @@
 */
 
 #include <linux/rtc.h>
+#include <linux/sched.h>
 #include <linux/log2.h>
 
 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)