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/wireless/b43legacy/phy.c b/drivers/net/wireless/b43legacy/phy.c
index 11319ec..aaf2272 100644
--- a/drivers/net/wireless/b43legacy/phy.c
+++ b/drivers/net/wireless/b43legacy/phy.c
@@ -31,6 +31,7 @@
 
 #include <linux/delay.h>
 #include <linux/pci.h>
+#include <linux/sched.h>
 #include <linux/types.h>
 
 #include "b43legacy.h"