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/char/epca.c b/drivers/char/epca.c
index 9d589e3..dde5134 100644
--- a/drivers/char/epca.c
+++ b/drivers/char/epca.c
@@ -30,6 +30,7 @@
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/init.h>
+#include <linux/sched.h>
 #include <linux/serial.h>
 #include <linux/delay.h>
 #include <linux/ctype.h>