Fixed implementation to disallow setting Bluetooth device
address under active advertising or scanning states.
Fixes LL.TS.5.0.2 conformance tests:
LL/CON/INI/BV-01-C [Connection Initiation]
LL/SEC/ADV/BV-01-C [Advertising With Static Address]
LL/SEC/SCN/BV-01-C [Random Address Scanning]
Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>