bluetooth: controller: Control procedure collision with Encryption and PHY update procedure

[joerchan]

Description:
Bluetooth controller can initiate LL encryption procedure whyle LL phy update procedure is in progress.
This is a violation of the Bluetooth specification, only one LL control procedure can be initiated by one side at a time.
If the peer side is behaving as expected it shall drop the connection with error code LPM transaction collision.

To reproduce
Using bluetooth central_hr sample
Requires control of the peer side in responding.
Run an advertiser with 16 bit Heart Rate UUID in advertise packet.
Respond to security request before responding to PHY update procedure.
Connection will disconnect with LMP transaction collision.

Expected behaviour:
Encryption request shall not be initiated before LL Phy update procedure has completed.

Impact:
Both timing and behaviour dependant.
Can result in connection failures sometimes.
Worst case two peers are unable to establish a connection.

enc_phy_collision.zip

Environment

• OS: Linux
• Toolchain Zephyr SDK
• a1c2159