net: ieee802154: drop duplicate header delay.h

Drop duplicate header delay.h from adf7242.c.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Acked-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ieee802154/adf7242.c

@@ -20,7 +20,6 @@
 #include <linux/skbuff.h>
 #include <linux/of.h>
 #include <linux/irq.h>
-#include <linux/delay.h>
 #include <linux/debugfs.h>
 #include <linux/bitops.h>
 #include <linux/ieee802154.h>