Abnormal RSSI when pairing is ongoing

Application:
simple_peripheral

Problem Reproducibility:

100%

Problem Description:

RSSI returns a positive value when pairing is ongoing. The RSSI value returns as expected for non-encrypted packets.

Steps to re-create the problem:

1. Import simple_peripheral
2. Add code to store the RSSI in a buffer named test_RSSI_buff
3. Flash the modified binary to a launchpad.
4. Connect to the peripheral using a phone.
5. Trigger a pairing session. At this point, once the device is paired/bonded successfully you should see at least one entry inside the buffer.
6. If you disconnect the phone and reconnect to the peripheral, you will see a number of abnormal entries in the buffer

Fix:
Encrypted packets have a different payload structure than non-encrypted packets. The different packet structure and length should be taken into account so that the returned RSSI is correctly parsed and passed up to the application. This was fixed in the link layer in the stack.