Bluetooth: controller: Fix assert on different transaction collision

Updated the implementation of PHY update procedure to not
assert when peer master violates the Bluetooth Specification
v5.0 Vol.6 Part B Section 5.3 Procedure Collisions. Instead
disconnect the link with reason Different Transaction
Collision (0x2A).

Certain phones in the market perform Connection Update
Procedure and do not correctly handle remote initiated
colliding PHY update procedures. They try to perform both
the transactions involving an instant simultaneously
violating the Bluetooth Specifications.

Implementation in Zephyr is updated to gracefully handle
the violating remote master device, and not fatally assert
in the local device.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>