Add support for two MAC addresses.  If the NVS has a valid MAC
address, that takes precedence and we use two sequential address
starting from the one specified.

If the NVS doesn't contain a valid MAC address (ie. if it is set to
00:00:00:00:00:00), we check if the HW PG version in use has the
BD_ADDR written in the fuse ROM.  If it does, we read it and derive
the two subsequent addresses for WLAN.

During production, 3 addresses are reserved per device.  The first for
Bluetooth (burnt in the fuse ROM) and the following two for WLAN.

This patch has some code by Igal and Arik (squashed from internal
patches).
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Igal Chernobelsky <igalc@ti.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>