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/iwlwifi/iwl-5000.c b/drivers/net/wireless/iwlwifi/iwl-5000.c
index eb08f44..d6bc0e0 100644
--- a/drivers/net/wireless/iwlwifi/iwl-5000.c
+++ b/drivers/net/wireless/iwlwifi/iwl-5000.c
@@ -29,6 +29,7 @@
 #include <linux/pci.h>
 #include <linux/dma-mapping.h>
 #include <linux/delay.h>
+#include <linux/sched.h>
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
 #include <linux/wireless.h>