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/mtd/devices/sst25l.c b/drivers/mtd/devices/sst25l.c
index c2baf33..0a11721 100644
--- a/drivers/mtd/devices/sst25l.c
+++ b/drivers/mtd/devices/sst25l.c
@@ -20,6 +20,7 @@
 #include <linux/device.h>
 #include <linux/mutex.h>
 #include <linux/interrupt.h>
+#include <linux/sched.h>
 
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/partitions.h>