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/iwmc3200wifi/main.c b/drivers/net/wireless/iwmc3200wifi/main.c
index d668e47..222eb2c 100644
--- a/drivers/net/wireless/iwmc3200wifi/main.c
+++ b/drivers/net/wireless/iwmc3200wifi/main.c
@@ -38,6 +38,7 @@
 
 #include <linux/kernel.h>
 #include <linux/netdevice.h>
+#include <linux/sched.h>
 #include <linux/ieee80211.h>
 #include <linux/wireless.h>