bt_keys_get_addr creates a new entry if none is found so it cannot be used
to detect if the device have been paired, instead use bt_keys_find_addr.
Change-Id: I0fd1de4b6e3a0652d36aa70d50074fb5013fa99d
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>