Bluetooth: Controller: Implement Broadcast ISO PTO calculation

[cvinayak]

Is your enhancement proposal related to a problem? Please describe.

• Implement the calculation of PTO in the Zephyr Controller to fully support Broadcast ISO feature.
• Execution and Identity conformance failure, Broadcast ISO PTO related tests
• Implement missing PTO related code and fix bugs discovered during testing

The transport latency for a BIG is the actual latency of transmitting payloads of
all BISes in the BIG, and calculates as:

Transport_Latency_BIG = BIG_Sync_Delay + PTO × (NSE ÷ BN –
IRC) * ISO_Interval + ISO_Interval + SDU_Interval

The calculated transport latencies shall be less than or equal to those set by
the Host.

Describe the solution you'd like

• Identify and Run PTO related conformance tests
• Implement the calculation of PTO

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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