ieee802154: 6lowpan: remove EXPORT_SYMBOL

This function is used internally inside of ieee802154 6lowpan module
only and not outside of any other module. We don't need to export this
function then.

Reviewed-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/ieee802154/6lowpan/reassembly.c

@@ -387,7 +387,6 @@ err:
 	kfree_skb(skb);
 	return -1;
 }
-EXPORT_SYMBOL(lowpan_frag_rcv);
 
 #ifdef CONFIG_SYSCTL
 static int zero;