Bluetooth: 6LoWPAN: Fix MAC address universal/local bit handling

The universal/local bit handling was incorrectly done in the code.

So when setting EUI address from BD address we do this:
- If BD address type is PUBLIC, then we clear the universal bit
  in EUI address. If the address type is RANDOM, then the universal
  bit is set (BT 6lowpan draft chapter 3.2.2)
- After this we invert the universal/local bit according to RFC 2464

When figuring out BD address we do the reverse:
- Take EUI address from stateless IPv6 address, invert the
  universal/local bit according to RFC 2464
- If universal bit is 1 in this modified EUI address, then address
  type is set to RANDOM, otherwise it is PUBLIC

Note that 6lowpan_iphc.[ch] does the final toggling of U/L bit
before sending or receiving the network packet.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable@vger.kernel.org