Bluetooth: remove unused including <linux/version.h>

Remove including <linux/version.h> that don't need it.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/6lowpan.c

@@ -11,7 +11,6 @@
    GNU General Public License for more details.
 */
 
-#include <linux/version.h>
 #include <linux/if_arp.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>