Bluetooth: Controller: df: Wrong antenna identifier inserted after switch pattern exhausted

[ppryga-nordic]

Describe the bug
Antenna switch pattern is not correctly applied in case a CTE length is enough to exhaust the switch pattern.

During the reception of CTE in AoA mode or transmission of CTE in AoD mode radio switches antennas according to user provided switching pattern.
Take as an example that there is an antenna switch pattern provided by user to controller e.g.: A0, A1, A2, A3, A4.
Antenna A0 is used during GUARD and REFERENCE period. After that antennas A1, A2, A3, A4 are used.
Assume the CTE is long enough to exhaust the antenna switch pattern. Controller should apply antenna from the beginning of switch pattern which is reference antenna.
|REF|S1|S2|S3|S4|S5|S6|S7|S8|S9|S10|S11|S12|S13|S14|Switching slots|
|A0|A1|A2|A3|A4|A0|A1|A2|A3|A4|A0|A1|A2|A3|A4|BT Core compliant ant. application:|
|A0|A1|A2|A3|A4|A1|A2|A3|A4|A1|A2|A3|A4|A1|A2|Nordic default ant. Application:|

To Reproduce
Build direction finding samples that transmit and receive CTE.
Connect logic analyzer to GPIO outputs responsible for antenna switching.
Check logic levels that represent antenna ids from a switch pattern.

Expected behavior
Reference antenna should be inserted every time the switch pattern is loopback.

Impact
Minor, concerns DF use cases only.