Bluetooth: Remove 'own_addr' from advertising parameters

This was originally added as a work-around to avoid the heavy stack
consumption of the TinyCrypt PRNG when generating NRPAs. This is
no-longer an issue, and there are in fact no (in-tree) users of this.
Remove it before it gains any wider users, since it was in many ways a
hack/work-around to begin with.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>