net: openthread: Add openthread tcat multiradio config.

As per BHC-750 in TCAT case for now only allowed devices
are the ones that have either dual radio or multiplexed
radio capabilities. So the 'M' bit in BLE advertisement
should be always set to 1. In future specifications
devices without multiradio capabilities will be allowed
this is the reason why new Kconfig was introduced.

Signed-off-by: Przemyslaw Bida <przemyslaw.bida@nordicsemi.no>